import copy
import inspect
import warnings
from dataclasses import dataclass
from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Tuple, Union
import torch
import torch.distributed as dist
from torch import nn
from ..deepspeed import is_deepspeed_zero3_enabled
from ..modeling_outputs import CausalLMOutputWithPast, Seq2SeqLMOutput
from ..models.auto import (
MODEL_FOR_CAUSAL_IMAGE_MODELING_MAPPING,
MODEL_FOR_CAUSAL_LM_MAPPING,
MODEL_FOR_SEQ_TO_SEQ_CAUSAL_LM_MAPPING,
MODEL_FOR_SPEECH_SEQ_2_SEQ_MAPPING,
MODEL_FOR_VISION_2_SEQ_MAPPING,
)
from ..utils import ModelOutput, logging
from .beam_constraints import DisjunctiveConstraint, PhrasalConstraint
from .beam_search import BeamScorer, BeamSearchScorer, ConstrainedBeamSearchScorer
from .configuration_utils import GenerationConfig
from .logits_process import (
EncoderNoRepeatNGramLogitsProcessor,
EncoderRepetitionPenaltyLogitsProcessor,
EpsilonLogitsWarper,
EtaLogitsWarper,
ExponentialDecayLengthPenalty,
ForcedBOSTokenLogitsProcessor,
ForcedEOSTokenLogitsProcessor,
ForceTokensLogitsProcessor,
HammingDiversityLogitsProcessor,
InfNanRemoveLogitsProcessor,
LogitNormalization,
LogitsProcessorList,
MinLengthLogitsProcessor,
MinNewTokensLengthLogitsProcessor,
NoBadWordsLogitsProcessor,
NoRepeatNGramLogitsProcessor,
PrefixConstrainedLogitsProcessor,
RepetitionPenaltyLogitsProcessor,
SuppressTokensAtBeginLogitsProcessor,
SuppressTokensLogitsProcessor,
TemperatureLogitsWarper,
TopKLogitsWarper,
TopPLogitsWarper,
TypicalLogitsWarper,
)
from .stopping_criteria import (
MaxLengthCriteria,
MaxTimeCriteria,
StoppingCriteria,
StoppingCriteriaList,
validate_stopping_criteria,
)
if TYPE_CHECKING:
from ..modeling_utils import PreTrainedModel
from .streamers import BaseStreamer
logger = logging.get_logger(__name__)
@dataclass
class GreedySearchDecoderOnlyOutput(ModelOutput):
"""
Base class for outputs of decoder-only generation models using greedy search.
Args:
sequences (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
if all batches finished early due to the `eos_token_id`.
scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Processed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
each generated token), with each tensor of shape `(batch_size, config.vocab_size)`.
attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, generated_length, hidden_size)`.
"""
sequences: torch.LongTensor = None
scores: Optional[Tuple[torch.FloatTensor]] = None
attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
hidden_states: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
@dataclass
class ContrastiveSearchEncoderDecoderOutput(ModelOutput):
"""
Base class for outputs of decoder-only generation models using contrastive search.
Args:
sequences (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
if all batches finished early due to the `eos_token_id`.
scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Processed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
each generated token), with each tensor of shape `(batch_size, config.vocab_size)`.
encoder_attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer of the decoder) of shape `(batch_size, num_heads,
sequence_length, sequence_length)`.
encoder_hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of
shape `(batch_size, sequence_length, hidden_size)`.
decoder_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
cross_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
decoder_hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, generated_length, hidden_size)`.
"""
sequences: torch.LongTensor = None
scores: Optional[Tuple[torch.FloatTensor]] = None
encoder_attentions: Optional[Tuple[torch.FloatTensor]] = None
encoder_hidden_states: Optional[Tuple[torch.FloatTensor]] = None
decoder_attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
cross_attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
decoder_hidden_states: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
@dataclass
class ContrastiveSearchDecoderOnlyOutput(ModelOutput):
"""
Base class for outputs of decoder-only generation models using contrastive search.
Args:
sequences (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
if all batches finished early due to the `eos_token_id`.
scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True` is passed or when
`config.output_scores=True`):
Processed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
each generated token), with each tensor of shape `(batch_size, config.vocab_size)`.
attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True` is
passed or when `config.output_hidden_states=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, generated_length, hidden_size)`.
"""
sequences: torch.LongTensor = None
scores: Optional[Tuple[torch.FloatTensor]] = None
attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
hidden_states: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
@dataclass
class GreedySearchEncoderDecoderOutput(ModelOutput):
"""
Base class for outputs of encoder-decoder generation models using greedy search. Hidden states and attention
weights of the decoder (respectively the encoder) can be accessed via the encoder_attentions and the
encoder_hidden_states attributes (respectively the decoder_attentions and the decoder_hidden_states attributes)
Args:
sequences (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
if all batches finished early due to the `eos_token_id`.
scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Processed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
each generated token), with each tensor of shape `(batch_size, config.vocab_size)`.
encoder_attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer of the decoder) of shape `(batch_size, num_heads,
sequence_length, sequence_length)`.
encoder_hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of
shape `(batch_size, sequence_length, hidden_size)`.
decoder_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
cross_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
decoder_hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, generated_length, hidden_size)`.
"""
sequences: torch.LongTensor = None
scores: Optional[Tuple[torch.FloatTensor]] = None
encoder_attentions: Optional[Tuple[torch.FloatTensor]] = None
encoder_hidden_states: Optional[Tuple[torch.FloatTensor]] = None
decoder_attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
cross_attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
decoder_hidden_states: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
@dataclass
class SampleDecoderOnlyOutput(ModelOutput):
"""
Base class for outputs of decoder-only generation models using sampling.
Args:
sequences (`torch.LongTensor` of shape `(batch_size*num_return_sequences, sequence_length)`):
The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
if all batches finished early due to the `eos_token_id`.
scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Processed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
each generated token), with each tensor of shape `(batch_size*num_return_sequences, config.vocab_size)`.
attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(num_return_sequences*batch_size, num_heads, generated_length,
sequence_length)`.
hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(num_return_sequences*batch_size, generated_length, hidden_size)`.
"""
sequences: torch.LongTensor = None
scores: Optional[Tuple[torch.FloatTensor]] = None
attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
hidden_states: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
@dataclass
class SampleEncoderDecoderOutput(ModelOutput):
"""
Base class for outputs of encoder-decoder generation models using sampling. Hidden states and attention weights of
the decoder (respectively the encoder) can be accessed via the encoder_attentions and the encoder_hidden_states
attributes (respectively the decoder_attentions and the decoder_hidden_states attributes)
Args:
sequences (`torch.LongTensor` of shape `(batch_size*num_return_sequences, sequence_length)`):
The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
if all batches finished early due to the `eos_token_id`.
scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Processed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
each generated token), with each tensor of shape `(batch_size*num_return_sequences, config.vocab_size)`.
encoder_attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer of the decoder) of shape
`(batch_size*num_return_sequences, num_heads, sequence_length, sequence_length)`.
encoder_hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of
shape `(batch_size*num_return_sequences, sequence_length, hidden_size)`.
decoder_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size*num_return_sequences, num_heads, generated_length,
sequence_length)`.
cross_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
decoder_hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size*num_return_sequences, generated_length, hidden_size)`.
"""
sequences: torch.LongTensor = None
scores: Optional[Tuple[torch.FloatTensor]] = None
encoder_attentions: Optional[Tuple[torch.FloatTensor]] = None
encoder_hidden_states: Optional[Tuple[torch.FloatTensor]] = None
decoder_attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
cross_attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
decoder_hidden_states: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
@dataclass
class BeamSearchDecoderOnlyOutput(ModelOutput):
"""
Base class for outputs of decoder-only generation models using beam search.
Args:
sequences (`torch.LongTensor` of shape `(batch_size*num_return_sequences, sequence_length)`):
The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
if all batches finished early due to the `eos_token_id`.
sequences_scores (`torch.FloatTensor` of shape `(batch_size*num_return_sequences)`, *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Final beam scores of the generated `sequences`.
scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Beam transition scores for each vocabulary token at each generation step. Beam transition scores consisting
of log probabilities of tokens conditioned on log softmax of previously generated tokens in this beam.
Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for each generated token),
with each tensor of shape `(batch_size*num_beams*num_return_sequences, config.vocab_size)`.
beam_indices (`torch.LongTensor`, *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Beam indices of generated token id at each generation step. `torch.LongTensor` of shape
`(batch_size*num_return_sequences, sequence_length)`.
attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size*num_beams, num_heads, generated_length, sequence_length)`.
hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size*num_beams*num_return_sequences, generated_length, hidden_size)`.
"""
sequences: torch.LongTensor = None
sequences_scores: Optional[torch.FloatTensor] = None
scores: Optional[Tuple[torch.FloatTensor]] = None
beam_indices: Optional[torch.LongTensor] = None
attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
hidden_states: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
@dataclass
class BeamSearchEncoderDecoderOutput(ModelOutput):
"""
Base class for outputs of encoder-decoder generation models using beam search. Hidden states and attention weights
of the decoder (respectively the encoder) can be accessed via the encoder_attentions and the encoder_hidden_states
attributes (respectively the decoder_attentions and the decoder_hidden_states attributes)
Args:
sequences (`torch.LongTensor` of shape `(batch_size*num_return_sequences, sequence_length)`):
The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
if all batches finished early due to the `eos_token_id`.
sequences_scores (`torch.FloatTensor` of shape `(batch_size*num_return_sequences)`, *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Final beam scores of the generated `sequences`.
scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Beam transition scores for each vocabulary token at each generation step. Beam transition scores consisting
of log probabilities of tokens conditioned on log softmax of previously generated tokens in this beam.
Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for each generated token),
with each tensor of shape `(batch_size*num_beams, config.vocab_size)`.
beam_indices (`torch.LongTensor`, *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Beam indices of generated token id at each generation step. `torch.LongTensor` of shape
`(batch_size*num_return_sequences, sequence_length)`.
encoder_attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer of the decoder) of shape `(batch_size, num_heads,
sequence_length, sequence_length)`.
encoder_hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of
shape `(batch_size*num_beams*num_return_sequences, sequence_length, hidden_size)`.
decoder_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size*num_beams*num_return_sequences, num_heads, generated_length,
sequence_length)`.
cross_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
decoder_hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size*num_beams*num_return_sequences, generated_length, hidden_size)`.
"""
sequences: torch.LongTensor = None
sequences_scores: Optional[torch.FloatTensor] = None
scores: Optional[Tuple[torch.FloatTensor]] = None
beam_indices: Optional[torch.LongTensor] = None
encoder_attentions: Optional[Tuple[torch.FloatTensor]] = None
encoder_hidden_states: Optional[Tuple[torch.FloatTensor]] = None
decoder_attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
cross_attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
decoder_hidden_states: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
@dataclass
class BeamSampleDecoderOnlyOutput(ModelOutput):
"""
Base class for outputs of decoder-only generation models using beam sample.
Args:
sequences (`torch.LongTensor` of shape `(batch_size*num_return_sequences, sequence_length)`):
The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
if all batches finished early due to the `eos_token_id`.
sequences_scores (`torch.FloatTensor` of shape `(batch_size * num_return_sequence)`, *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Final beam scores of the generated `sequences`.
scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Beam transition scores for each vocabulary token at each generation step. Beam transition scores consisting
of log probabilities of tokens conditioned on log softmax of previously generated tokens in this beam.
Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for each generated token),
with each tensor of shape `(batch_size*num_beams*num_return_sequences, config.vocab_size)`.
beam_indices (`torch.LongTensor`, *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Beam indices of generated token id at each generation step. `torch.LongTensor` of shape
`(batch_size*num_return_sequences, sequence_length)`.
attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size*num_beams, num_heads, generated_length, sequence_length)`.
hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size*num_beams, generated_length, hidden_size)`.
"""
sequences: torch.LongTensor = None
sequences_scores: Optional[torch.FloatTensor] = None
scores: Optional[Tuple[torch.FloatTensor]] = None
beam_indices: Optional[torch.LongTensor] = None
attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
hidden_states: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
@dataclass
class BeamSampleEncoderDecoderOutput(ModelOutput):
"""
Base class for outputs of encoder-decoder generation models using beam sampling. Hidden states and attention
weights of the decoder (respectively the encoder) can be accessed via the encoder_attentions and the
encoder_hidden_states attributes (respectively the decoder_attentions and the decoder_hidden_states attributes)
Args:
sequences (`torch.LongTensor` of shape `(batch_size*num_beams, sequence_length)`):
The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
if all batches finished early due to the `eos_token_id`.
sequences_scores (`torch.FloatTensor` of shape `(batch_size * num_return_sequence)`, *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Final beam scores of the generated `sequences`.
scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Beam transition scores for each vocabulary token at each generation step. Beam transition scores consisting
of log probabilities of tokens conditioned on log softmax of previously generated tokens in this beam.
Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for each generated token),
with each tensor of shape `(batch_size*num_beams, config.vocab_size)`).
beam_indices (`torch.LongTensor`, *optional*, returned when `output_scores=True` is passed or when `config.output_scores=True`):
Beam indices of generated token id at each generation step. `torch.LongTensor` of shape
`(batch_size*num_return_sequences, sequence_length)`.
encoder_attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer of the decoder) of shape `(batch_size, num_heads,
sequence_length, sequence_length)`.
encoder_hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of
shape `(batch_size*num_beams, sequence_length, hidden_size)`.
decoder_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size*num_beams, num_heads, generated_length, sequence_length)`.
cross_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True` is passed or `config.output_attentions=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
decoder_hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
`torch.FloatTensor` of shape `(batch_size*num_beams, generated_length, hidden_size)`.
"""
sequences: torch.LongTensor = None
sequences_scores: Optional[torch.FloatTensor] = None
scores: Optional[Tuple[torch.FloatTensor]] = None
beam_indices: Optional[torch.LongTensor] = None
encoder_attentions: Optional[Tuple[torch.FloatTensor]] = None
encoder_hidden_states: Optional[Tuple[torch.FloatTensor]] = None
decoder_attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
cross_attentions: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
decoder_hidden_states: Optional[Tuple[Tuple[torch.FloatTensor]]] = None
GreedySearchOutput = Union[GreedySearchEncoderDecoderOutput, GreedySearchDecoderOnlyOutput]
SampleOutput = Union[SampleEncoderDecoderOutput, SampleDecoderOnlyOutput]
BeamSearchOutput = Union[BeamSearchEncoderDecoderOutput, BeamSearchDecoderOnlyOutput]
BeamSampleOutput = Union[BeamSampleEncoderDecoderOutput, BeamSampleDecoderOnlyOutput]
ContrastiveSearchOutput = Union[ContrastiveSearchEncoderDecoderOutput, ContrastiveSearchDecoderOnlyOutput]
GenerateOutput = Union[GreedySearchOutput, SampleOutput, BeamSearchOutput, BeamSampleOutput, ContrastiveSearchOutput]
class GenerationMixin:
"""
A class containing all functions for auto-regressive text generation, to be used as a mixin in [`PreTrainedModel`].
The class exposes [`~generation.GenerationMixin.generate`], which can be used for:
- *greedy decoding* by calling [`~generation.GenerationMixin.greedy_search`] if `num_beams=1` and
`do_sample=False`
- *contrastive search* by calling [`~generation.GenerationMixin.contrastive_search`] if `penalty_alpha>0` and
`top_k>1`
- *multinomial sampling* by calling [`~generation.GenerationMixin.sample`] if `num_beams=1` and
`do_sample=True`
- *beam-search decoding* by calling [`~generation.GenerationMixin.beam_search`] if `num_beams>1` and
`do_sample=False`
- *beam-search multinomial sampling* by calling [`~generation.GenerationMixin.beam_sample`] if `num_beams>1`
and `do_sample=True`
- *diverse beam-search decoding* by calling [`~generation.GenerationMixin.group_beam_search`], if `num_beams>1`
and `num_beam_groups>1`
- *constrained beam-search decoding* by calling [`~generation.GenerationMixin.constrained_beam_search`], if
`constraints!=None` or `force_words_ids!=None`
You do not need to call any of the above methods directly. Pass custom parameter values to 'generate' instead. To
learn more about decoding strategies refer to the [text generation strategies guide](../generation_strategies).
"""
def prepare_inputs_for_generation(self, *args, **kwargs):
raise NotImplementedError(
"A model class needs to define a `prepare_inputs_for_generation` method in order to use `.generate()`."
)
def _prepare_model_inputs(
self,
inputs: Optional[torch.Tensor] = None,
bos_token_id: Optional[int] = None,
model_kwargs: Optional[Dict[str, torch.Tensor]] = None,
) -> Tuple[torch.Tensor, Optional[str], Dict[str, torch.Tensor]]:
"""
This function extracts the model-specific `inputs` for generation.
"""
if (
self.config.is_encoder_decoder
and hasattr(self, "encoder")
and self.encoder.main_input_name != self.main_input_name
):
input_name = self.encoder.main_input_name
else:
input_name = self.main_input_name
model_kwargs = {k: v for k, v in model_kwargs.items() if v is not None or k != input_name}
inputs_kwarg = model_kwargs.pop(input_name, None)
if inputs_kwarg is not None and inputs is not None:
raise ValueError(
f"`inputs`: {inputs}` were passed alongside {input_name} which is not allowed."
f"Make sure to either pass {inputs} or {input_name}=..."
)
elif inputs_kwarg is not None:
inputs = inputs_kwarg
if input_name == "input_ids" and "inputs_embeds" in model_kwargs:
if not self.config.is_encoder_decoder:
has_inputs_embeds_forwarding = "inputs_embeds" in set(
inspect.signature(self.prepare_inputs_for_generation).parameters.keys()
)
if not has_inputs_embeds_forwarding:
raise ValueError(
f"You passed `inputs_embeds` to `.generate()`, but the model class {self.__class__.__name__} "
"doesn't have its forwarding implemented. See the GPT2 implementation for an example "
"(https://github.com/huggingface/transformers/pull/21405), and feel free to open a PR with it!"
)
model_kwargs["input_ids"] = self._maybe_initialize_input_ids_for_generation(
inputs, bos_token_id, model_kwargs=model_kwargs
)
else:
if inputs is not None:
raise ValueError("You passed `inputs_embeds` and `input_ids` to `.generate()`. Please pick one.")
inputs, input_name = model_kwargs["inputs_embeds"], "inputs_embeds"
inputs = self._maybe_initialize_input_ids_for_generation(inputs, bos_token_id, model_kwargs)
return inputs, input_name, model_kwargs
def adjust_logits_during_generation(self, logits: torch.FloatTensor, **kwargs) -> torch.FloatTensor:
"""
Implement in subclasses of [`PreTrainedModel`] for custom behavior to adjust the logits in the generate method.
"""
return logits
def _maybe_initialize_input_ids_for_generation(
self,
inputs: Optional[torch.Tensor] = None,
bos_token_id: Optional[int] = None,
model_kwargs: Optional[Dict[str, torch.Tensor]] = None,
) -> torch.LongTensor:
"""Initializes input ids for generation, if necessary."""
if inputs is not None:
return inputs
encoder_outputs = model_kwargs.get("encoder_outputs")
if self.config.is_encoder_decoder and encoder_outputs is not None:
shape = encoder_outputs.last_hidden_state.size()[:-1]
return torch.ones(shape, dtype=torch.long, device=self.device) * -100
if bos_token_id is None:
raise ValueError("`bos_token_id` has to be defined when no `input_ids` are provided.")
batch_size = 1
for value in model_kwargs.values():
if isinstance(value, torch.Tensor):
batch_size = value.shape[0]
break
return torch.ones((batch_size, 1), dtype=torch.long, device=self.device) * bos_token_id
def _prepare_attention_mask_for_generation(
self,
inputs: torch.Tensor,
pad_token_id: Optional[int],
eos_token_id: Optional[Union[int, List[int]]],
) -> torch.LongTensor:
is_input_ids = len(inputs.shape) == 2 and inputs.dtype in [torch.int, torch.long]
is_pad_token_in_inputs = (pad_token_id is not None) and (pad_token_id in inputs)
if isinstance(eos_token_id, int):
eos_token_id = [eos_token_id]
is_pad_token_not_equal_to_eos_token_id = (eos_token_id is None) or (pad_token_id not in eos_token_id)
if is_input_ids and is_pad_token_in_inputs and is_pad_token_not_equal_to_eos_token_id:
return inputs.ne(pad_token_id).long()
else:
return torch.ones(inputs.shape[:2], dtype=torch.long, device=inputs.device)
def _prepare_encoder_decoder_kwargs_for_generation(
self, inputs_tensor: torch.Tensor, model_kwargs, model_input_name: Optional[str] = None
) -> Dict[str, Any]:
encoder = self.get_encoder()
irrelevant_prefix = ["decoder_", "cross_attn", "use_cache"]
encoder_kwargs = {
argument: value
for argument, value in model_kwargs.items()
if not any(argument.startswith(p) for p in irrelevant_prefix)
}
encoder_signature = set(inspect.signature(encoder.forward).parameters)
encoder_accepts_wildcard = "kwargs" in encoder_signature or "model_kwargs" in encoder_signature
if not encoder_accepts_wildcard:
encoder_kwargs = {
argument: value for argument, value in encoder_kwargs.items() if argument in encoder_signature
}
model_input_name = model_input_name if model_input_name is not None else self.main_input_name
encoder_kwargs["return_dict"] = True
encoder_kwargs[model_input_name] = inputs_tensor
model_kwargs["encoder_outputs"]: ModelOutput = encoder(**encoder_kwargs)
return model_kwargs
def _prepare_decoder_input_ids_for_generation(
self,
batch_size: int,
model_input_name: str,
model_kwargs: Dict[str, torch.Tensor],
decoder_start_token_id: int = None,
bos_token_id: int = None,
device: torch.device = None,
) -> Tuple[torch.LongTensor, Dict[str, torch.Tensor]]:
"""Prepares `decoder_input_ids` for generation with encoder-decoder models"""
if model_kwargs is not None and "decoder_input_ids" in model_kwargs:
decoder_input_ids = model_kwargs.pop("decoder_input_ids")
elif "input_ids" in model_kwargs and model_input_name != "input_ids":
decoder_input_ids = model_kwargs.pop("input_ids")
else:
decoder_input_ids = None
decoder_start_token_id = self._get_decoder_start_token_id(decoder_start_token_id, bos_token_id)
if device is None:
device = self.device
decoder_input_ids_start = torch.ones((batch_size, 1), dtype=torch.long, device=device) * decoder_start_token_id
if decoder_input_ids is None:
decoder_input_ids = decoder_input_ids_start
elif self.config.model_type == "vision-encoder-decoder" and "donut" in self.name_or_path.lower():
pass
elif (decoder_input_ids[:, 0] != decoder_start_token_id).all().item():
decoder_input_ids = torch.cat([decoder_input_ids_start, decoder_input_ids], dim=-1)
if "decoder_attention_mask" in model_kwargs:
decoder_attention_mask = model_kwargs["decoder_attention_mask"]
decoder_attention_mask = torch.cat(
(torch.ones_like(decoder_attention_mask)[:, :1], decoder_attention_mask),
dim=-1,
)
model_kwargs["decoder_attention_mask"] = decoder_attention_mask
return decoder_input_ids, model_kwargs
def _get_decoder_start_token_id(self, decoder_start_token_id: int = None, bos_token_id: int = None) -> int:
decoder_start_token_id = (
decoder_start_token_id
if decoder_start_token_id is not None
else self.generation_config.decoder_start_token_id
)
bos_token_id = bos_token_id if bos_token_id is not None else self.generation_config.bos_token_id
if decoder_start_token_id is not None:
return decoder_start_token_id
elif bos_token_id is not None:
return bos_token_id
raise ValueError(
"`decoder_start_token_id` or `bos_token_id` has to be defined for encoder-decoder generation."
)
@staticmethod
def _expand_inputs_for_generation(
expand_size: int = 1,
is_encoder_decoder: bool = False,
input_ids: Optional[torch.LongTensor] = None,
**model_kwargs,
) -> Tuple[torch.LongTensor, Dict[str, Any]]:
"""Expands tensors from [batch_size, ...] to [batch_size * expand_size, ...]"""
def _expand_dict_for_generation(dict_to_expand):
for key in dict_to_expand:
if dict_to_expand[key] is not None and isinstance(dict_to_expand[key], torch.Tensor):
dict_to_expand[key] = dict_to_expand[key].repeat_interleave(expand_size, dim=0)
return dict_to_expand
if input_ids is not None:
input_ids = input_ids.repeat_interleave(expand_size, dim=0)
model_kwargs = _expand_dict_for_generation(model_kwargs)
if is_encoder_decoder:
if model_kwargs.get("encoder_outputs") is None:
raise ValueError("If `is_encoder_decoder` is True, make sure that `encoder_outputs` is defined.")
model_kwargs["encoder_outputs"] = _expand_dict_for_generation(model_kwargs["encoder_outputs"])
return input_ids, model_kwargs
def _extract_past_from_model_output(self, outputs: ModelOutput, standardize_cache_format: bool = False):
past_key_values = None
if "past_key_values" in outputs:
past_key_values = outputs.past_key_values
elif "mems" in outputs:
past_key_values = outputs.mems
elif "past_buckets_states" in outputs:
past_key_values = outputs.past_buckets_states
if standardize_cache_format and hasattr(self, "_convert_to_standard_cache"):
batch_size = outputs.logits.shape[0]
past_key_values = self._convert_to_standard_cache(past_key_values, batch_size=batch_size)
return past_key_values
def _update_model_kwargs_for_generation(
self,
outputs: ModelOutput,
model_kwargs: Dict[str, Any],
is_encoder_decoder: bool = False,
standardize_cache_format: bool = False,
) -> Dict[str, Any]:
model_kwargs["past_key_values"] = self._extract_past_from_model_output(
outputs, standardize_cache_format=standardize_cache_format
)
if getattr(outputs, "state", None) is not None:
model_kwargs["state"] = outputs.state
if "token_type_ids" in model_kwargs:
token_type_ids = model_kwargs["token_type_ids"]
model_kwargs["token_type_ids"] = torch.cat([token_type_ids, token_type_ids[:, -1].unsqueeze(-1)], dim=-1)
if not is_encoder_decoder:
if "attention_mask" in model_kwargs:
attention_mask = model_kwargs["attention_mask"]
model_kwargs["attention_mask"] = torch.cat(
[attention_mask, attention_mask.new_ones((attention_mask.shape[0], 1))], dim=-1
)
else:
if "decoder_attention_mask" in model_kwargs:
decoder_attention_mask = model_kwargs["decoder_attention_mask"]
model_kwargs["decoder_attention_mask"] = torch.cat(
[decoder_attention_mask, decoder_attention_mask.new_ones((decoder_attention_mask.shape[0], 1))],
dim=-1,
)
return model_kwargs
def _reorder_cache(self, past_key_values, beam_idx):
raise NotImplementedError(
f"Make sure that a `_reorder_cache` function is correctly implemented in {self.__class__.__module__} to"
f" enable beam search for {self.__class__}"
)
def _get_logits_warper(
self,
generation_config: GenerationConfig,
) -> LogitsProcessorList:
"""
This class returns a [`LogitsProcessorList`] list object that contains all relevant [`LogitsWarper`] instances
used for multinomial sampling.
"""
warpers = LogitsProcessorList()
if generation_config.temperature is not None and generation_config.temperature != 1.0:
warpers.append(TemperatureLogitsWarper(generation_config.temperature))
min_tokens_to_keep = 2 if generation_config.num_beams > 1 else 1
if generation_config.top_k is not None and generation_config.top_k != 0:
warpers.append(TopKLogitsWarper(top_k=generation_config.top_k, min_tokens_to_keep=min_tokens_to_keep))
if generation_config.top_p is not None and generation_config.top_p < 1.0:
warpers.append(TopPLogitsWarper(top_p=generation_config.top_p, min_tokens_to_keep=min_tokens_to_keep))
if generation_config.typical_p is not None and generation_config.typical_p < 1.0:
warpers.append(
TypicalLogitsWarper(mass=generation_config.typical_p, min_tokens_to_keep=min_tokens_to_keep)
)
if generation_config.epsilon_cutoff is not None and 0.0 < generation_config.epsilon_cutoff < 1.0:
warpers.append(
EpsilonLogitsWarper(epsilon=generation_config.epsilon_cutoff, min_tokens_to_keep=min_tokens_to_keep)
)
if generation_config.eta_cutoff is not None and 0.0 < generation_config.eta_cutoff < 1.0:
warpers.append(
EtaLogitsWarper(epsilon=generation_config.eta_cutoff, min_tokens_to_keep=min_tokens_to_keep)
)
if generation_config.renormalize_logits is True:
warpers.append(LogitNormalization())
return warpers
def _get_logits_processor(
self,
generation_config: GenerationConfig,
input_ids_seq_length: int,
encoder_input_ids: torch.LongTensor,
prefix_allowed_tokens_fn: Callable[[int, torch.Tensor], List[int]],
logits_processor: Optional[LogitsProcessorList],
) -> LogitsProcessorList:
"""
This class returns a [`LogitsProcessorList`] list object that contains all relevant [`LogitsProcessor`]
instances used to modify the scores of the language model head.
"""
processors = LogitsProcessorList()
if generation_config.diversity_penalty is not None and generation_config.diversity_penalty > 0.0:
processors.append(
HammingDiversityLogitsProcessor(
diversity_penalty=generation_config.diversity_penalty,
num_beams=generation_config.num_beams,
num_beam_groups=generation_config.num_beam_groups,
)
)
if (
generation_config.encoder_repetition_penalty is not None
and generation_config.encoder_repetition_penalty != 1.0
):
processors.append(
EncoderRepetitionPenaltyLogitsProcessor(
penalty=generation_config.encoder_repetition_penalty, encoder_input_ids=encoder_input_ids
)
)
if generation_config.repetition_penalty is not None and generation_config.repetition_penalty != 1.0:
processors.append(RepetitionPenaltyLogitsProcessor(penalty=generation_config.repetition_penalty))
if generation_config.no_repeat_ngram_size is not None and generation_config.no_repeat_ngram_size > 0:
processors.append(NoRepeatNGramLogitsProcessor(generation_config.no_repeat_ngram_size))
if (
generation_config.encoder_no_repeat_ngram_size is not None
and generation_config.encoder_no_repeat_ngram_size > 0
):
if self.config.is_encoder_decoder:
processors.append(
EncoderNoRepeatNGramLogitsProcessor(
generation_config.encoder_no_repeat_ngram_size, encoder_input_ids
)
)
else:
raise ValueError(
"It's impossible to use `encoder_no_repeat_ngram_size` with decoder-only architecture"
)
if generation_config.bad_words_ids is not None:
processors.append(
NoBadWordsLogitsProcessor(generation_config.bad_words_ids, generation_config.eos_token_id)
)
if (
generation_config.min_length is not None
and generation_config.eos_token_id is not None
and generation_config.min_length > 0
):
processors.append(MinLengthLogitsProcessor(generation_config.min_length, generation_config.eos_token_id))
if (
generation_config.min_new_tokens is not None
and generation_config.eos_token_id is not None
and generation_config.min_new_tokens > 0
):
processors.append(
MinNewTokensLengthLogitsProcessor(
input_ids_seq_length, generation_config.min_new_tokens, generation_config.eos_token_id
)
)
if prefix_allowed_tokens_fn is not None:
processors.append(
PrefixConstrainedLogitsProcessor(
prefix_allowed_tokens_fn, generation_config.num_beams // generation_config.num_beam_groups
)
)
if generation_config.forced_bos_token_id is not None:
processors.append(ForcedBOSTokenLogitsProcessor(generation_config.forced_bos_token_id))
if generation_config.forced_eos_token_id is not None:
processors.append(
ForcedEOSTokenLogitsProcessor(generation_config.max_length, generation_config.forced_eos_token_id)
)
if generation_config.remove_invalid_values is True:
processors.append(InfNanRemoveLogitsProcessor())
if generation_config.exponential_decay_length_penalty is not None:
processors.append(
ExponentialDecayLengthPenalty(
generation_config.exponential_decay_length_penalty,
generation_config.eos_token_id,
input_ids_seq_length,
)
)
if generation_config.suppress_tokens is not None:
processors.append(SuppressTokensLogitsProcessor(generation_config.suppress_tokens))
if generation_config.begin_suppress_tokens is not None:
begin_index = input_ids_seq_length
begin_index = (
begin_index
if (input_ids_seq_length > 1 or generation_config.forced_bos_token_id is None)
else begin_index + 1
)
if generation_config.forced_decoder_ids is not None:
begin_index += generation_config.forced_decoder_ids[-1][0]
processors.append(
SuppressTokensAtBeginLogitsProcessor(generation_config.begin_suppress_tokens, begin_index)
)
if generation_config.forced_decoder_ids is not None:
processors.append(ForceTokensLogitsProcessor(generation_config.forced_decoder_ids))
processors = self._merge_criteria_processor_list(processors, logits_processor)
if generation_config.renormalize_logits is True:
processors.append(LogitNormalization())
return processors
def _get_stopping_criteria(
self, generation_config: GenerationConfig, stopping_criteria: Optional[StoppingCriteriaList]
) -> StoppingCriteriaList:
criteria = StoppingCriteriaList()
if generation_config.max_length is not None:
criteria.append(MaxLengthCriteria(max_length=generation_config.max_length))
if generation_config.max_time is not None:
criteria.append(MaxTimeCriteria(max_time=generation_config.max_time))
criteria = self._merge_criteria_processor_list(criteria, stopping_criteria)
return criteria
def _merge_criteria_processor_list(
self,
default_list: Union[LogitsProcessorList, StoppingCriteriaList],
custom_list: Union[LogitsProcessorList, StoppingCriteriaList],
) -> Union[LogitsProcessorList, StoppingCriteriaList]:
if len(custom_list) == 0:
return default_list
for default in default_list:
for custom in custom_list:
if type(custom) is type(default):
object_type = "stopping criteria" if isinstance(custom, StoppingCriteria) else "logits processor"
raise ValueError(
f"A custom {object_type} of type {type(custom)} with values {custom} has been passed to"
f" `.generate()`, but it has already been created with the values {default}. {default} has been"
" created by passing the corresponding arguments to generate or by the model's config default"
f" values. If you just want to change the default values of {object_type} consider passing"
f" them as arguments to `.generate()` instead of using a custom {object_type}."
)
default_list.extend(custom_list)
return default_list
def compute_transition_scores(
self,
sequences: torch.Tensor,
scores: Tuple[torch.Tensor],
beam_indices: Optional[torch.Tensor] = None,
normalize_logits: bool = False,
) -> torch.Tensor:
"""
Computes the transition scores of sequences given the generation scores (and beam indices, if beam search was
used). This is a convenient method to quicky obtain the scores of the selected tokens at generation time.
Parameters:
sequences (`torch.LongTensor`):
The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or
shorter if all batches finished early due to the `eos_token_id`.
scores (`tuple(torch.FloatTensor)`):
Transition scores for each vocabulary token at each generation step. Beam transition scores consisting
of log probabilities of tokens conditioned on log softmax of previously generated tokens Tuple of
`torch.FloatTensor` with up to `max_new_tokens` elements (one element for each generated token), with
each tensor of shape `(batch_size*num_beams, config.vocab_size)`.
beam_indices (`torch.LongTensor`, *optional*):
Beam indices of generated token id at each generation step. `torch.LongTensor` of shape
`(batch_size*num_return_sequences, sequence_length)`. Only required if a `num_beams>1` at
generate-time.
normalize_logits (`bool`, *optional*, defaults to `False`):
Whether to normalize the logits (which, for legacy reasons, may be unnormalized).
Return:
`torch.Tensor`: A `torch.Tensor` of shape `(batch_size*num_return_sequences, sequence_length)` containing
the transition scores (logits)
Examples:
```python
>>> from transformers import GPT2Tokenizer, AutoModelForCausalLM
>>> import numpy as np
>>> tokenizer = GPT2Tokenizer.from_pretrained("gpt2")
>>> model = AutoModelForCausalLM.from_pretrained("gpt2")
>>> tokenizer.pad_token_id = tokenizer.eos_token_id
>>> inputs = tokenizer(["Today is"], return_tensors="pt")
>>> # Example 1: Print the scores for each token generated with Greedy Search
>>> outputs = model.generate(**inputs, max_new_tokens=5, return_dict_in_generate=True, output_scores=True)
>>> transition_scores = model.compute_transition_scores(
... outputs.sequences, outputs.scores, normalize_logits=True
... )
>>> # input_length is the length of the input prompt for decoder-only models, like the GPT family, and 1 for
>>> # encoder-decoder models, like BART or T5.
>>> input_length = 1 if model.config.is_encoder_decoder else inputs.input_ids.shape[1]
>>> generated_tokens = outputs.sequences[:, input_length:]
>>> for tok, score in zip(generated_tokens[0], transition_scores[0]):
... # | token | token string | logits | probability
... print(f"| {tok:5d} | {tokenizer.decode(tok):8s} | {score.numpy():.3f} | {np.exp(score.numpy()):.2%}")
| 262 | the | -1.414 | 24.33%
| 1110 | day | -2.609 | 7.36%
| 618 | when | -2.010 | 13.40%
| 356 | we | -1.859 | 15.58%
| 460 | can | -2.508 | 8.14%
>>> # Example 2: Reconstruct the sequence scores from Beam Search
>>> outputs = model.generate(
... **inputs,
... max_new_tokens=5,
... num_beams=4,
... num_return_sequences=4,
... return_dict_in_generate=True,
... output_scores=True,
... )
>>> transition_scores = model.compute_transition_scores(
... outputs.sequences, outputs.scores, outputs.beam_indices, normalize_logits=False
... )
>>> # If you sum the generated tokens' scores and apply the length penalty, you'll get the sequence scores.
>>> # Tip: recomputing the scores is only guaranteed to match with `normalize_logits=False`. Depending on the
>>> # use case, you might want to recompute it with `normalize_logits=True`.
>>> output_length = input_length + np.sum(transition_scores.numpy() < 0, axis=1)
>>> length_penalty = model.generation_config.length_penalty
>>> reconstructed_scores = transition_scores.sum(axis=1) / (output_length**length_penalty)
>>> print(np.allclose(outputs.sequences_scores, reconstructed_scores))
True
```"""
if beam_indices is None:
beam_indices = torch.arange(scores[0].shape[0]).view(-1, 1).to(sequences.device)
beam_indices = beam_indices.expand(-1, len(scores))
scores = torch.stack(scores).reshape(len(scores), -1).transpose(0, 1)
if normalize_logits:
scores = scores.reshape(-1, self.config.vocab_size, scores.shape[-1])
scores = torch.nn.functional.log_softmax(scores, dim=1)
scores = scores.reshape(-1, scores.shape[-1])
beam_indices_mask = beam_indices < 0
max_beam_length = (1 - beam_indices_mask.long()).sum(-1).max()
beam_indices = beam_indices.clone()[:, :max_beam_length]
beam_indices_mask = beam_indices_mask[:, :max_beam_length]
beam_indices[beam_indices_mask] = 0
beam_sequence_indices = beam_indices * self.config.vocab_size
cut_idx = sequences.shape[-1] - max_beam_length
indices = sequences[:, cut_idx:] + beam_sequence_indices
transition_scores = scores.gather(0, indices)
transition_scores[beam_indices_mask] = 0
return transition_scores
def _validate_model_class(self):
"""
Confirms that the model class is compatible with generation. If not, raises an exception that points to the
right class to use.
"""
if not self.can_generate():
generate_compatible_mappings = [
MODEL_FOR_CAUSAL_LM_MAPPING,
MODEL_FOR_CAUSAL_IMAGE_MODELING_MAPPING,
MODEL_FOR_VISION_2_SEQ_MAPPING,
MODEL_FOR_SEQ_TO_SEQ_CAUSAL_LM_MAPPING,
MODEL_FOR_SPEECH_SEQ_2_SEQ_MAPPING,
]
generate_compatible_classes = set()
for model_mapping in generate_compatible_mappings:
supported_models = model_mapping.get(type(self.config), default=None)
if supported_models is not None:
generate_compatible_classes.add(supported_models.__name__)
exception_message = (
f"The current model class ({self.__class__.__name__}) is not compatible with `.generate()`, as "
"it doesn't have a language model head."
)
if generate_compatible_classes:
exception_message += f" Please use one of the following classes instead: {generate_compatible_classes}"
raise TypeError(exception_message)
def _validate_model_kwargs(self, model_kwargs: Dict[str, Any]):
"""Validates model kwargs for generation. Generate argument typos will also be caught here."""
if self.config.is_encoder_decoder:
for key in ["decoder_input_ids"]:
model_kwargs.pop(key, None)
unused_model_args = []
model_args = set(inspect.signature(self.prepare_inputs_for_generation).parameters)
if "kwargs" in model_args or "model_kwargs" in model_args:
model_args |= set(inspect.signature(self.forward).parameters)
for key, value in model_kwargs.items():
if value is not None and key not in model_args:
unused_model_args.append(key)
if unused_model_args:
raise ValueError(
f"The following `model_kwargs` are not used by the model: {unused_model_args} (note: typos in the"
" generate arguments will also show up in this list)"
)
@torch.no_grad()
def generate(
self,
inputs: Optional[torch.Tensor] = None,
generation_config: Optional[GenerationConfig] = None,
logits_processor: Optional[LogitsProcessorList] = None,
stopping_criteria: Optional[StoppingCriteriaList] = None,
prefix_allowed_tokens_fn: Optional[Callable[[int, torch.Tensor], List[int]]] = None,
synced_gpus: Optional[bool] = None,
assistant_model: Optional["PreTrainedModel"] = None,
streamer: Optional["BaseStreamer"] = None,
**kwargs,
) -> Union[GenerateOutput, torch.LongTensor]:
r"""
Generates sequences of token ids for models with a language modeling head.
<Tip warning={true}>
Most generation-controlling parameters are set in `generation_config` which, if not passed, will be set to the
model's default generation configuration. You can override any `generation_config` by passing the corresponding
parameters to generate(), e.g. `.generate(inputs, num_beams=4, do_sample=True)`.
For an overview of generation strategies and code examples, check out the [following
guide](../generation_strategies).
</Tip>
Parameters:
inputs (`torch.Tensor` of varying shape depending on the modality, *optional*):
The sequence used as a prompt for the generation or as model inputs to the encoder. If `None` the
method initializes it with `bos_token_id` and a batch size of 1. For decoder-only models `inputs`
should of in the format of `input_ids`. For encoder-decoder models *inputs* can represent any of
`input_ids`, `input_values`, `input_features`, or `pixel_values`.
generation_config (`~generation.GenerationConfig`, *optional*):
The generation configuration to be used as base parametrization for the generation call. `**kwargs`
passed to generate matching the attributes of `generation_config` will override them. If
`generation_config` is not provided, the default will be used, which had the following loading
priority: 1) from the `generation_config.json` model file, if it exists; 2) from the model
configuration. Please note that unspecified parameters will inherit [`~generation.GenerationConfig`]'s
default values, whose documentation should be checked to parameterize generation.
logits_processor (`LogitsProcessorList`, *optional*):
Custom logits processors that complement the default logits processors built from arguments and
generation config. If a logit processor is passed that is already created with the arguments or a
generation config an error is thrown. This feature is intended for advanced users.
stopping_criteria (`StoppingCriteriaList`, *optional*):
Custom stopping criteria that complement the default stopping criteria built from arguments and a
generation config. If a stopping criteria is passed that is already created with the arguments or a
generation config an error is thrown. This feature is intended for advanced users.
prefix_allowed_tokens_fn (`Callable[[int, torch.Tensor], List[int]]`, *optional*):
If provided, this function constraints the beam search to allowed tokens only at each step. If not
provided no constraint is applied. This function takes 2 arguments: the batch ID `batch_id` and
`input_ids`. It has to return a list with the allowed tokens for the next generation step conditioned
on the batch ID `batch_id` and the previously generated tokens `inputs_ids`. This argument is useful
for constrained generation conditioned on the prefix, as described in [Autoregressive Entity
Retrieval](https://arxiv.org/abs/2010.00904).
synced_gpus (`bool`, *optional*):
Whether to continue running the while loop until max_length. Unless overridden this flag will be set to
`True` under DeepSpeed ZeRO Stage 3 multiple GPUs environment to avoid hanging if one GPU finished
generating before other GPUs. Otherwise it'll be set to `False`.
assistant_model (`PreTrainedModel`, *optional*):
An assistant model that can be used to accelerate generation. The assistant model must have the exact
same tokenizer. The acceleration is achieved when forecasting candidate tokens with the assistent model
is much faster than running generation with the model you're calling generate from. As such, the
assistant model should be much smaller.
streamer (`BaseStreamer`, *optional*):
Streamer object that will be used to stream the generated sequences. Generated tokens are passed
through `streamer.put(token_ids)` and the streamer is responsible for any further processing.
kwargs:
Ad hoc parametrization of `generate_config` and/or additional model-specific kwargs that will be
forwarded to the `forward` function of the model. If the model is an encoder-decoder model, encoder
specific kwargs should not be prefixed and decoder specific kwargs should be prefixed with *decoder_*.
Return:
[`~utils.ModelOutput`] or `torch.LongTensor`: A [`~utils.ModelOutput`] (if `return_dict_in_generate=True`
or when `config.return_dict_in_generate=True`) or a `torch.FloatTensor`.
If the model is *not* an encoder-decoder model (`model.config.is_encoder_decoder=False`), the possible
[`~utils.ModelOutput`] types are:
- [`~generation.GreedySearchDecoderOnlyOutput`],
- [`~generation.SampleDecoderOnlyOutput`],
- [`~generation.BeamSearchDecoderOnlyOutput`],
- [`~generation.BeamSampleDecoderOnlyOutput`]
If the model is an encoder-decoder model (`model.config.is_encoder_decoder=True`), the possible
[`~utils.ModelOutput`] types are:
- [`~generation.GreedySearchEncoderDecoderOutput`],
- [`~generation.SampleEncoderDecoderOutput`],
- [`~generation.BeamSearchEncoderDecoderOutput`],
- [`~generation.BeamSampleEncoderDecoderOutput`]
"""
if synced_gpus is None:
if is_deepspeed_zero3_enabled() and dist.get_world_size() > 1:
synced_gpus = True
else:
synced_gpus = False
self._validate_model_class()
if generation_config is None:
if self.generation_config._from_model_config:
new_generation_config = GenerationConfig.from_model_config(self.config)
if new_generation_config != self.generation_config:
warnings.warn(
"You have modified the pretrained model configuration to control generation. This is a"
" deprecated strategy to control generation and will be removed soon, in a future version."
" Please use a generation configuration file (see"
" https://huggingface.co/docs/transformers/main_classes/text_generation)"
)
self.generation_config = new_generation_config
generation_config = self.generation_config
generation_config = copy.deepcopy(generation_config)
model_kwargs = generation_config.update(**kwargs)
generation_config.validate()
self._validate_model_kwargs(model_kwargs.copy())
logits_processor = logits_processor if logits_processor is not None else LogitsProcessorList()
stopping_criteria = stopping_criteria if stopping_criteria is not None else StoppingCriteriaList()
if generation_config.pad_token_id is None and generation_config.eos_token_id is not None:
if model_kwargs.get("attention_mask", None) is None:
logger.warning(
"The attention mask and the pad token id were not set. As a consequence, you may observe "
"unexpected behavior. Please pass your input's `attention_mask` to obtain reliable results."
)
eos_token_id = generation_config.eos_token_id
if isinstance(eos_token_id, list):
eos_token_id = eos_token_id[0]
logger.warning(f"Setting `pad_token_id` to `eos_token_id`:{eos_token_id} for open-end generation.")
generation_config.pad_token_id = eos_token_id
inputs_tensor, model_input_name, model_kwargs = self._prepare_model_inputs(
inputs, generation_config.bos_token_id, model_kwargs
)
batch_size = inputs_tensor.shape[0]
model_kwargs["output_attentions"] = generation_config.output_attentions
model_kwargs["output_hidden_states"] = generation_config.output_hidden_states
model_kwargs["use_cache"] = generation_config.use_cache
accepts_attention_mask = "attention_mask" in set(inspect.signature(self.forward).parameters.keys())
requires_attention_mask = "encoder_outputs" not in model_kwargs
if model_kwargs.get("attention_mask", None) is None and requires_attention_mask and accepts_attention_mask:
model_kwargs["attention_mask"] = self._prepare_attention_mask_for_generation(
inputs_tensor, generation_config.pad_token_id, generation_config.eos_token_id
)
if not self.config.is_encoder_decoder:
if (
generation_config.pad_token_id is not None
and torch.sum(inputs_tensor[:, -1] == generation_config.pad_token_id) > 0
):
logger.warning(
"A decoder-only architecture is being used, but right-padding was detected! For correct "
"generation results, please set `padding_side='left'` when initializing the tokenizer."
)
if self.config.is_encoder_decoder and "encoder_outputs" not in model_kwargs:
model_kwargs = self._prepare_encoder_decoder_kwargs_for_generation(
inputs_tensor, model_kwargs, model_input_name
)
if self.config.is_encoder_decoder:
input_ids, model_kwargs = self._prepare_decoder_input_ids_for_generation(
batch_size=batch_size,
model_input_name=model_input_name,
model_kwargs=model_kwargs,
decoder_start_token_id=generation_config.decoder_start_token_id,
bos_token_id=generation_config.bos_token_id,
device=inputs_tensor.device,
)
else:
input_ids = inputs_tensor if model_input_name == "input_ids" else model_kwargs.pop("input_ids")
if streamer is not None:
streamer.put(input_ids.cpu())
input_ids_seq_length = input_ids.shape[-1]
has_default_max_length = kwargs.get("max_length") is None and generation_config.max_length is not None
if has_default_max_length and generation_config.max_new_tokens is None:
warnings.warn(
f"Using `max_length`'s default ({generation_config.max_length}) to control the generation length. "
"This behaviour is deprecated and will be removed from the config in v5 of Transformers -- we"
" recommend using `max_new_tokens` to control the maximum length of the generation.",
UserWarning,
)
elif generation_config.max_new_tokens is not None:
if not has_default_max_length:
logger.warning(
f"Both `max_new_tokens` (={generation_config.max_new_tokens}) and `max_length`(="
f"{generation_config.max_length}) seem to have been set. `max_new_tokens` will take precedence. "
"Please refer to the documentation for more information. "
"(https://huggingface.co/docs/transformers/main/en/main_classes/text_generation)"
)
generation_config.max_length = generation_config.max_new_tokens + input_ids_seq_length
if generation_config.min_length is not None and generation_config.min_length > generation_config.max_length:
raise ValueError(
f"Unfeasible length constraints: the minimum length ({generation_config.min_length}) is larger than"
f" the maximum length ({generation_config.max_length})"
)
if input_ids_seq_length >= generation_config.max_length:
input_ids_string = "decoder_input_ids" if self.config.is_encoder_decoder else "input_ids"
logger.warning(
f"Input length of {input_ids_string} is {input_ids_seq_length}, but `max_length` is set to"
f" {generation_config.max_length}. This can lead to unexpected behavior. You should consider"
" increasing `max_new_tokens`."
)
is_constraint_gen_mode = (
generation_config.constraints is not None or generation_config.force_words_ids is not None
)
is_contrastive_search_gen_mode = (
(generation_config.num_beams == 1)
and generation_config.top_k is not None
and generation_config.top_k > 1
and generation_config.do_sample is False
and generation_config.penalty_alpha is not None
and generation_config.penalty_alpha > 0
)
is_greedy_gen_mode = (
(generation_config.num_beams == 1)
and (generation_config.num_beam_groups == 1)
and generation_config.do_sample is False
and not is_constraint_gen_mode
and not is_contrastive_search_gen_mode
)
is_sample_gen_mode = (
(generation_config.num_beams == 1)
and (generation_config.num_beam_groups == 1)
and generation_config.do_sample is True
and not is_constraint_gen_mode
and not is_contrastive_search_gen_mode
)
is_beam_gen_mode = (
(generation_config.num_beams > 1)
and (generation_config.num_beam_groups == 1)
and generation_config.do_sample is False
and not is_constraint_gen_mode
and not is_contrastive_search_gen_mode
)
is_beam_sample_gen_mode = (
(generation_config.num_beams > 1)
and (generation_config.num_beam_groups == 1)
and generation_config.do_sample is True
and not is_constraint_gen_mode
and not is_contrastive_search_gen_mode
)
is_group_beam_gen_mode = (
(generation_config.num_beams > 1)
and (generation_config.num_beam_groups > 1)
and not is_constraint_gen_mode
and not is_contrastive_search_gen_mode
)
is_assisted_gen_mode = False
if assistant_model is not None:
if not (is_greedy_gen_mode or is_sample_gen_mode):
raise ValueError(
"You've set `assistant_model`, which triggers assisted generate. Currently, assisted generate "
"is only supported with Greedy Search and Sample."
)
is_assisted_gen_mode = True
if generation_config.num_beam_groups > generation_config.num_beams:
raise ValueError("`num_beam_groups` has to be smaller or equal to `num_beams`")
if is_group_beam_gen_mode and generation_config.do_sample is True:
raise ValueError(
"Diverse beam search cannot be used in sampling mode. Make sure that `do_sample` is set to `False`."
)
if streamer is not None and (generation_config.num_beams > 1):
raise ValueError(
"`streamer` cannot be used with beam search (yet!). Make sure that `num_beams` is set to 1."
)
if self.device.type != input_ids.device.type:
warnings.warn(
"You are calling .generate() with the `input_ids` being on a device type different"
f" than your model's device. `input_ids` is on {input_ids.device.type}, whereas the model"
f" is on {self.device.type}. You may experience unexpected behaviors or slower generation."
" Please make sure that you have put `input_ids` to the"
f" correct device by calling for example input_ids = input_ids.to('{self.device.type}') before"
" running `.generate()`.",
UserWarning,
)
logits_processor = self._get_logits_processor(
generation_config=generation_config,
input_ids_seq_length=input_ids_seq_length,
encoder_input_ids=inputs_tensor,
prefix_allowed_tokens_fn=prefix_allowed_tokens_fn,
logits_processor=logits_processor,
)
stopping_criteria = self._get_stopping_criteria(
generation_config=generation_config, stopping_criteria=stopping_criteria
)
if is_assisted_gen_mode:
if generation_config.num_return_sequences > 1:
raise ValueError(
"num_return_sequences has to be 1 when doing assisted generate, "
f"but is {generation_config.num_return_sequences}."
)
if batch_size > 1:
raise ValueError("assisted generate is only supported for batch_size = 1")
if not model_kwargs["use_cache"]:
raise ValueError("assisted generate requires `use_cache=True`")
if assistant_model.config.is_encoder_decoder:
assistant_model_kwargs = copy.deepcopy(model_kwargs)
inputs_tensor, model_input_name, assistant_model_kwargs = assistant_model._prepare_model_inputs(
inputs_tensor, assistant_model.generation_config.bos_token_id, assistant_model_kwargs
)
assistant_model_kwargs = assistant_model._prepare_encoder_decoder_kwargs_for_generation(
inputs_tensor, assistant_model_kwargs, model_input_name
)
model_kwargs["assistant_encoder_outputs"] = assistant_model_kwargs["encoder_outputs"]
return self.assisted_decoding(
input_ids,
assistant_model=assistant_model,
do_sample=generation_config.do_sample,
logits_processor=logits_processor,
logits_warper=self._get_logits_warper(generation_config) if generation_config.do_sample else None,
stopping_criteria=stopping_criteria,
pad_token_id=generation_config.pad_token_id,
eos_token_id=generation_config.eos_token_id,
output_scores=generation_config.output_scores,
return_dict_in_generate=generation_config.return_dict_in_generate,
synced_gpus=synced_gpus,
streamer=streamer,
**model_kwargs,
)
if is_greedy_gen_mode:
if generation_config.num_return_sequences > 1:
raise ValueError(
"num_return_sequences has to be 1 when doing greedy search, "
f"but is {generation_config.num_return_sequences}."
)
return self.greedy_search(
input_ids,
logits_processor=logits_processor,
stopping_criteria=stopping_criteria,
pad_token_id=generation_config.pad_token_id,
eos_token_id=generation_config.eos_token_id,
output_scores=generation_config.output_scores,
return_dict_in_generate=generation_config.return_dict_in_generate,
synced_gpus=synced_gpus,
streamer=streamer,
**model_kwargs,
)
elif is_contrastive_search_gen_mode:
if generation_config.num_return_sequences > 1:
raise ValueError(
"num_return_sequences has to be 1 when doing contrastive search, "
f"but is {generation_config.num_return_sequences}."
)
if not model_kwargs["use_cache"]:
raise ValueError("Contrastive search requires `use_cache=True`")
return self.contrastive_search(
input_ids,
top_k=generation_config.top_k,
penalty_alpha=generation_config.penalty_alpha,
logits_processor=logits_processor,
stopping_criteria=stopping_criteria,
pad_token_id=generation_config.pad_token_id,
eos_token_id=generation_config.eos_token_id,
output_scores=generation_config.output_scores,
return_dict_in_generate=generation_config.return_dict_in_generate,
synced_gpus=synced_gpus,
streamer=streamer,
**model_kwargs,
)
elif is_sample_gen_mode:
logits_warper = self._get_logits_warper(generation_config)
input_ids, model_kwargs = self._expand_inputs_for_generation(
input_ids=input_ids,
expand_size=generation_config.num_return_sequences,
is_encoder_decoder=self.config.is_encoder_decoder,
**model_kwargs,
)
return self.sample(
input_ids,
logits_processor=logits_processor,
logits_warper=logits_warper,
stopping_criteria=stopping_criteria,
pad_token_id=generation_config.pad_token_id,
eos_token_id=generation_config.eos_token_id,
output_scores=generation_config.output_scores,
return_dict_in_generate=generation_config.return_dict_in_generate,
synced_gpus=synced_gpus,
streamer=streamer,
**model_kwargs,
)
elif is_beam_gen_mode:
if generation_config.num_return_sequences > generation_config.num_beams:
raise ValueError("`num_return_sequences` has to be smaller or equal to `num_beams`.")
if stopping_criteria.max_length is None:
raise ValueError("`max_length` needs to be a stopping_criteria for now.")
beam_scorer = BeamSearchScorer(
batch_size=batch_size,
num_beams=generation_config.num_beams,
device=inputs_tensor.device,
length_penalty=generation_config.length_penalty,
do_early_stopping=generation_config.early_stopping,
num_beam_hyps_to_keep=generation_config.num_return_sequences,
max_length=generation_config.max_length,
)
input_ids, model_kwargs = self._expand_inputs_for_generation(
input_ids=input_ids,
expand_size=generation_config.num_beams,
is_encoder_decoder=self.config.is_encoder_decoder,
**model_kwargs,
)
return self.beam_search(
input_ids,
beam_scorer,
logits_processor=logits_processor,
stopping_criteria=stopping_criteria,
pad_token_id=generation_config.pad_token_id,
eos_token_id=generation_config.eos_token_id,
output_scores=generation_config.output_scores,
return_dict_in_generate=generation_config.return_dict_in_generate,
synced_gpus=synced_gpus,
**model_kwargs,
)
elif is_beam_sample_gen_mode:
logits_warper = self._get_logits_warper(generation_config)
if stopping_criteria.max_length is None:
raise ValueError("`max_length` needs to be a stopping_criteria for now.")
beam_scorer = BeamSearchScorer(
batch_size=batch_size * generation_config.num_return_sequences,
num_beams=generation_config.num_beams,
device=inputs_tensor.device,
length_penalty=generation_config.length_penalty,
do_early_stopping=generation_config.early_stopping,
max_length=generation_config.max_length,
)
input_ids, model_kwargs = self._expand_inputs_for_generation(
input_ids=input_ids,
expand_size=generation_config.num_beams * generation_config.num_return_sequences,
is_encoder_decoder=self.config.is_encoder_decoder,
**model_kwargs,
)
return self.beam_sample(
input_ids,
beam_scorer,
logits_processor=logits_processor,
logits_warper=logits_warper,
stopping_criteria=stopping_criteria,
pad_token_id=generation_config.pad_token_id,
eos_token_id=generation_config.eos_token_id,
output_scores=generation_config.output_scores,
return_dict_in_generate=generation_config.return_dict_in_generate,
synced_gpus=synced_gpus,
**model_kwargs,
)
elif is_group_beam_gen_mode:
if generation_config.num_return_sequences > generation_config.num_beams:
raise ValueError("`num_return_sequences` has to be smaller or equal to `num_beams`.")
if generation_config.num_beams % generation_config.num_beam_groups != 0:
raise ValueError("`num_beams` should be divisible by `num_beam_groups` for group beam search.")
if stopping_criteria.max_length is None:
raise ValueError("`max_length` needs to be a stopping_criteria for now.")
has_default_typical_p = kwargs.get("typical_p") is None and generation_config.typical_p == 1.0
if not has_default_typical_p:
raise ValueError("Decoder argument `typical_p` is not supported with beam groups.")
beam_scorer = BeamSearchScorer(
batch_size=batch_size,
num_beams=generation_config.num_beams,
device=inputs_tensor.device,
length_penalty=generation_config.length_penalty,
do_early_stopping=generation_config.early_stopping,
num_beam_hyps_to_keep=generation_config.num_return_sequences,
num_beam_groups=generation_config.num_beam_groups,
max_length=generation_config.max_length,
)
input_ids, model_kwargs = self._expand_inputs_for_generation(
input_ids=input_ids,
expand_size=generation_config.num_beams,
is_encoder_decoder=self.config.is_encoder_decoder,
**model_kwargs,
)
return self.group_beam_search(
input_ids,
beam_scorer,
logits_processor=logits_processor,
stopping_criteria=stopping_criteria,
pad_token_id=generation_config.pad_token_id,
eos_token_id=generation_config.eos_token_id,
output_scores=generation_config.output_scores,
return_dict_in_generate=generation_config.return_dict_in_generate,
synced_gpus=synced_gpus,
**model_kwargs,
)
elif is_constraint_gen_mode:
if generation_config.num_return_sequences > generation_config.num_beams:
raise ValueError("`num_return_sequences` has to be smaller or equal to `num_beams`.")
if stopping_criteria.max_length is None:
raise ValueError("`max_length` needs to be a stopping_criteria for now.")
if generation_config.num_beams <= 1:
raise ValueError("`num_beams` needs to be greater than 1 for constrained generation.")
if generation_config.do_sample:
raise ValueError("`do_sample` needs to be false for constrained generation.")
if generation_config.num_beam_groups is not None and generation_config.num_beam_groups > 1:
raise ValueError("`num_beam_groups` not supported yet for constrained generation.")
final_constraints = []
if generation_config.constraints is not None:
final_constraints = generation_config.constraints
if generation_config.force_words_ids is not None:
def typeerror():
raise ValueError(
"`force_words_ids` has to either be a `List[List[List[int]]]` or `List[List[int]]`"
f"of positive integers, but is {generation_config.force_words_ids}."
)
if (
not isinstance(generation_config.force_words_ids, list)
or len(generation_config.force_words_ids) == 0
):
typeerror()
for word_ids in generation_config.force_words_ids:
if isinstance(word_ids[0], list):
if not isinstance(word_ids, list) or len(word_ids) == 0:
typeerror()
if any(not isinstance(token_ids, list) for token_ids in word_ids):
typeerror()
if any(
any((not isinstance(token_id, int) or token_id < 0) for token_id in token_ids)
for token_ids in word_ids
):
typeerror()
constraint = DisjunctiveConstraint(word_ids)
else:
if not isinstance(word_ids, list) or len(word_ids) == 0:
typeerror()
if any((not isinstance(token_id, int) or token_id < 0) for token_id in word_ids):
typeerror()
constraint = PhrasalConstraint(word_ids)
final_constraints.append(constraint)
constrained_beam_scorer = ConstrainedBeamSearchScorer(
constraints=final_constraints,
batch_size=batch_size,
num_beams=generation_config.num_beams,
device=inputs_tensor.device,
length_penalty=generation_config.length_penalty,
do_early_stopping=generation_config.early_stopping,
num_beam_hyps_to_keep=generation_config.num_return_sequences,
max_length=generation_config.max_length,
)
input_ids, model_kwargs = self._expand_inputs_for_generation(
input_ids=input_ids,
expand_size=generation_config.num_beams,
is_encoder_decoder=self.config.is_encoder_decoder,
**model_kwargs,
)
return self.constrained_beam_search(
input_ids,
constrained_beam_scorer=constrained_beam_scorer,
logits_processor=logits_processor,
stopping_criteria=stopping_criteria,
pad_token_id=generation_config.pad_token_id,
eos_token_id=generation_config.eos_token_id,
output_scores=generation_config.output_scores,
return_dict_in_generate=generation_config.return_dict_in_generate,
synced_gpus=synced_gpus,
**model_kwargs,
)
@torch.no_grad()
def contrastive_search(
self,
input_ids: torch.LongTensor,
top_k: Optional[int] = 1,
penalty_alpha: Optional[float] = 0,
logits_processor: Optional[LogitsProcessorList] = None,
logits_warper: Optional[LogitsProcessorList] = None,
stopping_criteria: Optional[StoppingCriteriaList] = None,
pad_token_id: Optional[int] = None,
eos_token_id: Optional[Union[int, List[int]]] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
output_scores: Optional[bool] = None,
return_dict_in_generate: Optional[bool] = None,
synced_gpus: bool = False,
streamer: Optional["BaseStreamer"] = None,
**model_kwargs,
) -> Union[ContrastiveSearchOutput, torch.LongTensor]:
r"""
Generates sequences of token ids for models with a language modeling head using **contrastive search** and can
be used for text-decoder, text-to-text, speech-to-text, and vision-to-text models.
<Tip warning={true}>
In most cases, you do not need to call [`~generation.GenerationMixin.contrastive_search`] directly. Use
generate() instead. For an overview of generation strategies and code examples, check the [following
guide](../generation_strategies).
</Tip>
Parameters:
input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The sequence used as a prompt for the generation.
top_k (`int`, *optional*, defaults to 1):
The size of the candidate set that is used to re-rank for contrastive search
penalty_alpha (`float`, *optional*, defaults to 0):
The degeneration penalty for contrastive search; activate when it is larger than 0
logits_processor (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsProcessor`]
used to modify the prediction scores of the language modeling head applied at each generation step.
logits_warper (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsWarper`] used
to warp the prediction score distribution of the language modeling head applied before multinomial
sampling at each generation step.
stopping_criteria (`StoppingCriteriaList`, *optional*):
An instance of [`StoppingCriteriaList`]. List of instances of class derived from [`StoppingCriteria`]
used to tell if the generation loop should stop.
pad_token_id (`int`, *optional*):
The id of the *padding* token.
eos_token_id (`Union[int, List[int]]`, *optional*):
The id of the *end-of-sequence* token. Optionally, use a list to set multiple *end-of-sequence* tokens.
output_attentions (`bool`, *optional*, defaults to `False`):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under
returned tensors for more details.
output_hidden_states (`bool`, *optional*, defaults to `False`):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors
for more details.
output_scores (`bool`, *optional*, defaults to `False`):
Whether or not to return the prediction scores. See `scores` under returned tensors for more details.
return_dict_in_generate (`bool`, *optional*, defaults to `False`):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
synced_gpus (`bool`, *optional*, defaults to `False`):
Whether to continue running the while loop until max_length (needed for ZeRO stage 3)
streamer (`BaseStreamer`, *optional*):
Streamer object that will be used to stream the generated sequences. Generated tokens are passed
through `streamer.put(token_ids)` and the streamer is responsible for any further processing.
model_kwargs:
Additional model specific keyword arguments will be forwarded to the `forward` function of the model.
If model is an encoder-decoder model the kwargs should include `encoder_outputs`.
Return:
[`~generation.ContrastiveSearchDecoderOnlyOutput`], [`~generation.ContrastiveSearchEncoderDecoderOutput`]
or `torch.LongTensor`: A `torch.LongTensor` containing the generated tokens (default behaviour) or a
[`~generation.ContrastiveSearchDecoderOnlyOutput`] if `model.config.is_encoder_decoder=False` and
`return_dict_in_generate=True` or a [`~generation.ContrastiveSearchEncoderDecoderOutput`] if
`model.config.is_encoder_decoder=True`.
Examples:
```python
>>> from transformers import (
... AutoTokenizer,
... AutoModelForCausalLM,
... StoppingCriteriaList,
... MaxLengthCriteria,
... )
>>> tokenizer = AutoTokenizer.from_pretrained("facebook/opt-125m")
>>> model = AutoModelForCausalLM.from_pretrained("facebook/opt-125m")
>>> # set pad_token_id to eos_token_id because OPT does not have a PAD token
>>> model.config.pad_token_id = model.config.eos_token_id
>>> input_prompt = "DeepMind Company is"
>>> input_ids = tokenizer(input_prompt, return_tensors="pt")
>>> stopping_criteria = StoppingCriteriaList([MaxLengthCriteria(max_length=64)])
>>> outputs = model.contrastive_search(
... **input_ids, penalty_alpha=0.6, top_k=4, stopping_criteria=stopping_criteria
... )
>>> tokenizer.batch_decode(outputs, skip_special_tokens=True)
['DeepMind Company is a company that focuses on the development and commercialization of artificial intelligence (AI). DeepMind’s mission is to help people understand and solve problems that are difficult to solve in the world today.\n\nIn this post, we talk about the benefits of deep learning in business and how it']
```"""
logits_processor = logits_processor if logits_processor is not None else LogitsProcessorList()
logits_warper = logits_warper if logits_warper is not None else LogitsProcessorList()
stopping_criteria = stopping_criteria if stopping_criteria is not None else StoppingCriteriaList()
pad_token_id = pad_token_id if pad_token_id is not None else self.generation_config.pad_token_id
eos_token_id = eos_token_id if eos_token_id is not None else self.generation_config.eos_token_id
if isinstance(eos_token_id, int):
eos_token_id = [eos_token_id]
eos_token_id_tensor = torch.tensor(eos_token_id).to(input_ids.device) if eos_token_id is not None else None
output_scores = output_scores if output_scores is not None else self.generation_config.output_scores
output_attentions = (
output_attentions if output_attentions is not None else self.generation_config.output_attentions
)
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.generation_config.output_hidden_states
)
return_dict_in_generate = (
return_dict_in_generate
if return_dict_in_generate is not None
else self.generation_config.return_dict_in_generate
)
scores = () if (return_dict_in_generate and output_scores) else None
decoder_attentions = () if (return_dict_in_generate and output_attentions) else None
cross_attentions = () if (return_dict_in_generate and output_attentions) else None
decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None
if return_dict_in_generate and self.config.is_encoder_decoder:
encoder_attentions = model_kwargs["encoder_outputs"].get("attentions") if output_attentions else None
encoder_hidden_states = (
model_kwargs["encoder_outputs"].get("hidden_states") if output_hidden_states else None
)
unfinished_sequences = torch.ones(input_ids.shape[0], dtype=torch.long, device=input_ids.device)
this_peer_finished = False
batch_size = input_ids.shape[0]
while True:
if synced_gpus:
this_peer_finished_flag = torch.tensor(0.0 if this_peer_finished else 1.0).to(input_ids.device)
dist.all_reduce(this_peer_finished_flag, op=dist.ReduceOp.SUM)
if this_peer_finished_flag.item() == 0.0:
break
if model_kwargs.get("past_key_values") is None:
model_kwargs["use_cache"] = True
model_inputs = self.prepare_inputs_for_generation(input_ids, **model_kwargs)
outputs = self(
**model_inputs, return_dict=True, output_hidden_states=True, output_attentions=output_attentions
)
if self.config.is_encoder_decoder:
last_hidden_states = outputs.decoder_hidden_states[-1]
else:
last_hidden_states = outputs.hidden_states[-1]
logit_for_next_step = outputs.logits[:, -1, :]
model_kwargs = self._update_model_kwargs_for_generation(
outputs,
model_kwargs,
is_encoder_decoder=self.config.is_encoder_decoder,
standardize_cache_format=True,
)
_, model_kwargs = self._expand_inputs_for_generation(
expand_size=top_k, is_encoder_decoder=self.config.is_encoder_decoder, **model_kwargs
)
past_key_values = model_kwargs.get("past_key_values")
if past_key_values is None:
raise ValueError(
f"{self.__class__.__name__} does not support caching and therefore **can't** be used "
"for contrastive search."
)
elif (
not isinstance(past_key_values[0], (tuple, torch.Tensor))
or past_key_values[0][0].shape[0] != batch_size
):
raise ValueError(
f"{self.__class__.__name__} does not have a standard cache format and therefore **can't** be "
"used for contrastive search without further modifications."
)
logit_for_next_step = logits_processor(input_ids, logit_for_next_step)
logit_for_next_step = logits_warper(input_ids, logit_for_next_step)
next_probs = nn.functional.softmax(logit_for_next_step, dim=-1)
top_k_probs, top_k_ids = torch.topk(next_probs, dim=-1, k=top_k)
if return_dict_in_generate:
if output_scores:
scores += (logit_for_next_step,)
if output_attentions:
decoder_attentions += (
(outputs.decoder_attentions,) if self.config.is_encoder_decoder else (outputs.attentions,)
)
if self.config.is_encoder_decoder:
cross_attentions += (outputs.cross_attentions,)
if output_hidden_states:
decoder_hidden_states += (
(outputs.decoder_hidden_states,)
if self.config.is_encoder_decoder
else (outputs.hidden_states,)
)
new_key_values = []
for layer in model_kwargs["past_key_values"]:
items = []
for item in layer:
items.append(item.repeat_interleave(top_k, dim=0))
new_key_values.append(items)
model_kwargs["past_key_values"] = new_key_values
next_model_inputs = self.prepare_inputs_for_generation(top_k_ids.view(-1, 1), **model_kwargs)
outputs = self(
**next_model_inputs, return_dict=True, output_hidden_states=True, output_attentions=output_attentions
)
next_past_key_values = self._extract_past_from_model_output(outputs, standardize_cache_format=True)
logits = outputs.logits[:, -1, :]
if self.config.is_encoder_decoder:
next_hidden = outputs.decoder_hidden_states[-1]
full_hidden_states = outputs.decoder_hidden_states
else:
next_hidden = outputs.hidden_states[-1]
full_hidden_states = outputs.hidden_states
context_hidden = last_hidden_states.repeat_interleave(top_k, dim=0)
selected_idx = _ranking_fast(context_hidden, next_hidden, top_k_probs, penalty_alpha, top_k)
next_tokens = top_k_ids[range(len(top_k_ids)), selected_idx]
next_hidden = torch.stack(torch.split(next_hidden.squeeze(dim=1), top_k))
next_hidden = next_hidden[range(batch_size), selected_idx, :]
last_hidden_states = torch.cat([last_hidden_states, next_hidden.unsqueeze(1)], dim=1)
next_decoder_hidden_states = ()
for layer in full_hidden_states:
layer = torch.stack(torch.split(layer, top_k))[range(batch_size), selected_idx, :]
next_decoder_hidden_states += (layer,)
new_key_values = ()
for layer in next_past_key_values:
items = ()
for item in layer:
item = torch.stack(torch.split(item, top_k, dim=0))
item = item[range(batch_size), selected_idx, ...]
items += (item,)
new_key_values += (items,)
next_past_key_values = new_key_values
logit_for_next_step = torch.stack(torch.split(logits, top_k))[range(batch_size), selected_idx, :]
if self.config.is_encoder_decoder:
next_step_cross_attentions = ()
next_step_decoder_attentions = ()
if output_attentions:
for layer in outputs.cross_attentions:
layer = torch.stack(torch.split(layer, top_k, dim=0))[range(batch_size), selected_idx, ...]
next_step_cross_attentions += (layer,)
for layer in outputs.decoder_attentions:
layer = torch.stack(torch.split(layer, top_k, dim=0))[range(batch_size), selected_idx, ...]
next_step_decoder_attentions += (layer,)
outputs = Seq2SeqLMOutput(
past_key_values=next_past_key_values,
decoder_hidden_states=next_decoder_hidden_states,
decoder_attentions=next_step_decoder_attentions or None,
cross_attentions=next_step_cross_attentions or None,
)
else:
next_step_attentions = ()
if output_attentions:
for layer in outputs.attentions:
layer = torch.stack(torch.split(layer, top_k, dim=0))[range(batch_size), selected_idx, ...]
next_step_attentions += (layer,)
outputs = CausalLMOutputWithPast(
past_key_values=next_past_key_values,
hidden_states=next_decoder_hidden_states,
attentions=next_step_attentions or None,
)
if synced_gpus and this_peer_finished:
continue
if eos_token_id is not None:
if pad_token_id is None:
raise ValueError("If `eos_token_id` is defined, make sure that `pad_token_id` is defined.")
next_tokens = next_tokens * unfinished_sequences + pad_token_id * (1 - unfinished_sequences)
input_ids = torch.cat([input_ids, next_tokens[:, None]], dim=-1)
if streamer is not None:
streamer.put(next_tokens.cpu())
model_kwargs = self._update_model_kwargs_for_generation(
outputs, model_kwargs, is_encoder_decoder=self.config.is_encoder_decoder
)
if eos_token_id_tensor is not None:
unfinished_sequences = unfinished_sequences.mul(
next_tokens.tile(eos_token_id_tensor.shape[0], 1).ne(eos_token_id_tensor.unsqueeze(1)).prod(dim=0)
)
if unfinished_sequences.max() == 0:
this_peer_finished = True
if stopping_criteria(input_ids, scores):
this_peer_finished = True
if this_peer_finished and not synced_gpus:
break
if streamer is not None:
streamer.end()
if return_dict_in_generate:
if self.config.is_encoder_decoder:
return ContrastiveSearchEncoderDecoderOutput(
sequences=input_ids,
scores=scores,
encoder_attentions=encoder_attentions,
encoder_hidden_states=encoder_hidden_states,
decoder_attentions=decoder_attentions,
cross_attentions=cross_attentions,
decoder_hidden_states=decoder_hidden_states,
)
else:
return ContrastiveSearchDecoderOnlyOutput(
sequences=input_ids,
scores=scores,
attentions=decoder_attentions,
hidden_states=decoder_hidden_states,
)
else:
return input_ids
def greedy_search(
self,
input_ids: torch.LongTensor,
logits_processor: Optional[LogitsProcessorList] = None,
stopping_criteria: Optional[StoppingCriteriaList] = None,
max_length: Optional[int] = None,
pad_token_id: Optional[int] = None,
eos_token_id: Optional[Union[int, List[int]]] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
output_scores: Optional[bool] = None,
return_dict_in_generate: Optional[bool] = None,
synced_gpus: bool = False,
streamer: Optional["BaseStreamer"] = None,
**model_kwargs,
) -> Union[GreedySearchOutput, torch.LongTensor]:
r"""
Generates sequences of token ids for models with a language modeling head using **greedy decoding** and can be
used for text-decoder, text-to-text, speech-to-text, and vision-to-text models.
<Tip warning={true}>
In most cases, you do not need to call [`~generation.GenerationMixin.greedy_search`] directly. Use generate()
instead. For an overview of generation strategies and code examples, check the [following
guide](../generation_strategies).
</Tip>
Parameters:
input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The sequence used as a prompt for the generation.
logits_processor (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsProcessor`]
used to modify the prediction scores of the language modeling head applied at each generation step.
stopping_criteria (`StoppingCriteriaList`, *optional*):
An instance of [`StoppingCriteriaList`]. List of instances of class derived from [`StoppingCriteria`]
used to tell if the generation loop should stop.
max_length (`int`, *optional*, defaults to 20):
**DEPRECATED**. Use `logits_processor` or `stopping_criteria` directly to cap the number of generated
tokens. The maximum length of the sequence to be generated.
pad_token_id (`int`, *optional*):
The id of the *padding* token.
eos_token_id (`Union[int, List[int]]`, *optional*):
The id of the *end-of-sequence* token. Optionally, use a list to set multiple *end-of-sequence* tokens.
output_attentions (`bool`, *optional*, defaults to `False`):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under
returned tensors for more details.
output_hidden_states (`bool`, *optional*, defaults to `False`):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors
for more details.
output_scores (`bool`, *optional*, defaults to `False`):
Whether or not to return the prediction scores. See `scores` under returned tensors for more details.
return_dict_in_generate (`bool`, *optional*, defaults to `False`):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
synced_gpus (`bool`, *optional*, defaults to `False`):
Whether to continue running the while loop until max_length (needed for ZeRO stage 3)
streamer (`BaseStreamer`, *optional*):
Streamer object that will be used to stream the generated sequences. Generated tokens are passed
through `streamer.put(token_ids)` and the streamer is responsible for any further processing.
model_kwargs:
Additional model specific keyword arguments will be forwarded to the `forward` function of the model.
If model is an encoder-decoder model the kwargs should include `encoder_outputs`.
Return:
[`~generation.GreedySearchDecoderOnlyOutput`], [`~generation.GreedySearchEncoderDecoderOutput`] or
`torch.LongTensor`: A `torch.LongTensor` containing the generated tokens (default behaviour) or a
[`~generation.GreedySearchDecoderOnlyOutput`] if `model.config.is_encoder_decoder=False` and
`return_dict_in_generate=True` or a [`~generation.GreedySearchEncoderDecoderOutput`] if
`model.config.is_encoder_decoder=True`.
Examples:
```python
>>> from transformers import (
... AutoTokenizer,
... AutoModelForCausalLM,
... LogitsProcessorList,
... MinLengthLogitsProcessor,
... StoppingCriteriaList,
... MaxLengthCriteria,
... )
>>> tokenizer = AutoTokenizer.from_pretrained("gpt2")
>>> model = AutoModelForCausalLM.from_pretrained("gpt2")
>>> # set pad_token_id to eos_token_id because GPT2 does not have a PAD token
>>> model.generation_config.pad_token_id = model.generation_config.eos_token_id
>>> input_prompt = "It might be possible to"
>>> input_ids = tokenizer(input_prompt, return_tensors="pt").input_ids
>>> # instantiate logits processors
>>> logits_processor = LogitsProcessorList(
... [
... MinLengthLogitsProcessor(10, eos_token_id=model.generation_config.eos_token_id),
... ]
... )
>>> stopping_criteria = StoppingCriteriaList([MaxLengthCriteria(max_length=20)])
>>> outputs = model.greedy_search(
... input_ids, logits_processor=logits_processor, stopping_criteria=stopping_criteria
... )
>>> tokenizer.batch_decode(outputs, skip_special_tokens=True)
["It might be possible to get a better understanding of the nature of the problem, but it's not"]
```"""
logits_processor = logits_processor if logits_processor is not None else LogitsProcessorList()
stopping_criteria = stopping_criteria if stopping_criteria is not None else StoppingCriteriaList()
if max_length is not None:
warnings.warn(
"`max_length` is deprecated in this function, use"
" `stopping_criteria=StoppingCriteriaList([MaxLengthCriteria(max_length=max_length)])` instead.",
UserWarning,
)
stopping_criteria = validate_stopping_criteria(stopping_criteria, max_length)
pad_token_id = pad_token_id if pad_token_id is not None else self.generation_config.pad_token_id
eos_token_id = eos_token_id if eos_token_id is not None else self.generation_config.eos_token_id
if isinstance(eos_token_id, int):
eos_token_id = [eos_token_id]
eos_token_id_tensor = torch.tensor(eos_token_id).to(input_ids.device) if eos_token_id is not None else None
output_scores = output_scores if output_scores is not None else self.generation_config.output_scores
output_attentions = (
output_attentions if output_attentions is not None else self.generation_config.output_attentions
)
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.generation_config.output_hidden_states
)
return_dict_in_generate = (
return_dict_in_generate
if return_dict_in_generate is not None
else self.generation_config.return_dict_in_generate
)
scores = () if (return_dict_in_generate and output_scores) else None
decoder_attentions = () if (return_dict_in_generate and output_attentions) else None
cross_attentions = () if (return_dict_in_generate and output_attentions) else None
decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None
if return_dict_in_generate and self.config.is_encoder_decoder:
encoder_attentions = model_kwargs["encoder_outputs"].get("attentions") if output_attentions else None
encoder_hidden_states = (
model_kwargs["encoder_outputs"].get("hidden_states") if output_hidden_states else None
)
unfinished_sequences = torch.ones(input_ids.shape[0], dtype=torch.long, device=input_ids.device)
this_peer_finished = False
while True:
if synced_gpus:
this_peer_finished_flag = torch.tensor(0.0 if this_peer_finished else 1.0).to(input_ids.device)
dist.all_reduce(this_peer_finished_flag, op=dist.ReduceOp.SUM)
if this_peer_finished_flag.item() == 0.0:
break
model_inputs = self.prepare_inputs_for_generation(input_ids, **model_kwargs)
outputs = self(
**model_inputs,
return_dict=True,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
)
if synced_gpus and this_peer_finished:
continue
next_token_logits = outputs.logits[:, -1, :]
next_tokens_scores = logits_processor(input_ids, next_token_logits)
if return_dict_in_generate:
if output_scores:
scores += (next_tokens_scores,)
if output_attentions:
decoder_attentions += (
(outputs.decoder_attentions,) if self.config.is_encoder_decoder else (outputs.attentions,)
)
if self.config.is_encoder_decoder:
cross_attentions += (outputs.cross_attentions,)
if output_hidden_states:
decoder_hidden_states += (
(outputs.decoder_hidden_states,)
if self.config.is_encoder_decoder
else (outputs.hidden_states,)
)
next_tokens = torch.argmax(next_tokens_scores, dim=-1)
if eos_token_id is not None:
if pad_token_id is None:
raise ValueError("If `eos_token_id` is defined, make sure that `pad_token_id` is defined.")
next_tokens = next_tokens * unfinished_sequences + pad_token_id * (1 - unfinished_sequences)
input_ids = torch.cat([input_ids, next_tokens[:, None]], dim=-1)
if streamer is not None:
streamer.put(next_tokens.cpu())
model_kwargs = self._update_model_kwargs_for_generation(
outputs, model_kwargs, is_encoder_decoder=self.config.is_encoder_decoder
)
if eos_token_id_tensor is not None:
unfinished_sequences = unfinished_sequences.mul(
next_tokens.tile(eos_token_id_tensor.shape[0], 1).ne(eos_token_id_tensor.unsqueeze(1)).prod(dim=0)
)
if unfinished_sequences.max() == 0:
this_peer_finished = True
if stopping_criteria(input_ids, scores):
this_peer_finished = True
if this_peer_finished and not synced_gpus:
break
if streamer is not None:
streamer.end()
if return_dict_in_generate:
if self.config.is_encoder_decoder:
return GreedySearchEncoderDecoderOutput(
sequences=input_ids,
scores=scores,
encoder_attentions=encoder_attentions,
encoder_hidden_states=encoder_hidden_states,
decoder_attentions=decoder_attentions,
cross_attentions=cross_attentions,
decoder_hidden_states=decoder_hidden_states,
)
else:
return GreedySearchDecoderOnlyOutput(
sequences=input_ids,
scores=scores,
attentions=decoder_attentions,
hidden_states=decoder_hidden_states,
)
else:
return input_ids
def sample(
self,
input_ids: torch.LongTensor,
logits_processor: Optional[LogitsProcessorList] = None,
stopping_criteria: Optional[StoppingCriteriaList] = None,
logits_warper: Optional[LogitsProcessorList] = None,
max_length: Optional[int] = None,
pad_token_id: Optional[int] = None,
eos_token_id: Optional[Union[int, List[int]]] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
output_scores: Optional[bool] = None,
return_dict_in_generate: Optional[bool] = None,
synced_gpus: bool = False,
streamer: Optional["BaseStreamer"] = None,
**model_kwargs,
) -> Union[SampleOutput, torch.LongTensor]:
r"""
Generates sequences of token ids for models with a language modeling head using **multinomial sampling** and
can be used for text-decoder, text-to-text, speech-to-text, and vision-to-text models.
<Tip warning={true}>
In most cases, you do not need to call [`~generation.GenerationMixin.sample`] directly. Use generate() instead.
For an overview of generation strategies and code examples, check the [following
guide](../generation_strategies).
</Tip>
Parameters:
input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The sequence used as a prompt for the generation.
logits_processor (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsProcessor`]
used to modify the prediction scores of the language modeling head applied at each generation step.
stopping_criteria (`StoppingCriteriaList`, *optional*):
An instance of [`StoppingCriteriaList`]. List of instances of class derived from [`StoppingCriteria`]
used to tell if the generation loop should stop.
logits_warper (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsWarper`] used
to warp the prediction score distribution of the language modeling head applied before multinomial
sampling at each generation step.
max_length (`int`, *optional*, defaults to 20):
**DEPRECATED**. Use `logits_processor` or `stopping_criteria` directly to cap the number of generated
tokens. The maximum length of the sequence to be generated.
pad_token_id (`int`, *optional*):
The id of the *padding* token.
eos_token_id (`Union[int, List[int]]`, *optional*):
The id of the *end-of-sequence* token. Optionally, use a list to set multiple *end-of-sequence* tokens.
output_attentions (`bool`, *optional*, defaults to `False`):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under
returned tensors for more details.
output_hidden_states (`bool`, *optional*, defaults to `False`):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors
for more details.
output_scores (`bool`, *optional*, defaults to `False`):
Whether or not to return the prediction scores. See `scores` under returned tensors for more details.
return_dict_in_generate (`bool`, *optional*, defaults to `False`):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
synced_gpus (`bool`, *optional*, defaults to `False`):
Whether to continue running the while loop until max_length (needed for ZeRO stage 3)
streamer (`BaseStreamer`, *optional*):
Streamer object that will be used to stream the generated sequences. Generated tokens are passed
through `streamer.put(token_ids)` and the streamer is responsible for any further processing.
model_kwargs:
Additional model specific kwargs will be forwarded to the `forward` function of the model. If model is
an encoder-decoder model the kwargs should include `encoder_outputs`.
Return:
[`~generation.SampleDecoderOnlyOutput`], [`~generation.SampleEncoderDecoderOutput`] or `torch.LongTensor`:
A `torch.LongTensor` containing the generated tokens (default behaviour) or a
[`~generation.SampleDecoderOnlyOutput`] if `model.config.is_encoder_decoder=False` and
`return_dict_in_generate=True` or a [`~generation.SampleEncoderDecoderOutput`] if
`model.config.is_encoder_decoder=True`.
Examples:
```python
>>> from transformers import (
... AutoTokenizer,
... AutoModelForCausalLM,
... LogitsProcessorList,
... MinLengthLogitsProcessor,
... TopKLogitsWarper,
... TemperatureLogitsWarper,
... StoppingCriteriaList,
... MaxLengthCriteria,
... )
>>> import torch
>>> tokenizer = AutoTokenizer.from_pretrained("gpt2")
>>> model = AutoModelForCausalLM.from_pretrained("gpt2")
>>> # set pad_token_id to eos_token_id because GPT2 does not have a EOS token
>>> model.config.pad_token_id = model.config.eos_token_id
>>> model.generation_config.pad_token_id = model.config.eos_token_id
>>> input_prompt = "Today is a beautiful day, and"
>>> input_ids = tokenizer(input_prompt, return_tensors="pt").input_ids
>>> # instantiate logits processors
>>> logits_processor = LogitsProcessorList(
... [
... MinLengthLogitsProcessor(15, eos_token_id=model.generation_config.eos_token_id),
... ]
... )
>>> # instantiate logits processors
>>> logits_warper = LogitsProcessorList(
... [
... TopKLogitsWarper(50),
... TemperatureLogitsWarper(0.7),
... ]
... )
>>> stopping_criteria = StoppingCriteriaList([MaxLengthCriteria(max_length=20)])
>>> torch.manual_seed(0) # doctest: +IGNORE_RESULT
>>> outputs = model.sample(
... input_ids,
... logits_processor=logits_processor,
... logits_warper=logits_warper,
... stopping_criteria=stopping_criteria,
... )
>>> tokenizer.batch_decode(outputs, skip_special_tokens=True)
['Today is a beautiful day, and we must do everything possible to make it a day of celebration.']
```"""
logits_processor = logits_processor if logits_processor is not None else LogitsProcessorList()
stopping_criteria = stopping_criteria if stopping_criteria is not None else StoppingCriteriaList()
if max_length is not None:
warnings.warn(
"`max_length` is deprecated in this function, use"
" `stopping_criteria=StoppingCriteriaList(MaxLengthCriteria(max_length=max_length))` instead.",
UserWarning,
)
stopping_criteria = validate_stopping_criteria(stopping_criteria, max_length)
logits_warper = logits_warper if logits_warper is not None else LogitsProcessorList()
pad_token_id = pad_token_id if pad_token_id is not None else self.generation_config.pad_token_id
eos_token_id = eos_token_id if eos_token_id is not None else self.generation_config.eos_token_id
if isinstance(eos_token_id, int):
eos_token_id = [eos_token_id]
eos_token_id_tensor = torch.tensor(eos_token_id).to(input_ids.device) if eos_token_id is not None else None
output_scores = output_scores if output_scores is not None else self.generation_config.output_scores
output_attentions = (
output_attentions if output_attentions is not None else self.generation_config.output_attentions
)
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.generation_config.output_hidden_states
)
return_dict_in_generate = (
return_dict_in_generate
if return_dict_in_generate is not None
else self.generation_config.return_dict_in_generate
)
scores = () if (return_dict_in_generate and output_scores) else None
decoder_attentions = () if (return_dict_in_generate and output_attentions) else None
cross_attentions = () if (return_dict_in_generate and output_attentions) else None
decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None
if return_dict_in_generate and self.config.is_encoder_decoder:
encoder_attentions = model_kwargs["encoder_outputs"].get("attentions") if output_attentions else None
encoder_hidden_states = (
model_kwargs["encoder_outputs"].get("hidden_states") if output_hidden_states else None
)
unfinished_sequences = torch.ones(input_ids.shape[0], dtype=torch.long, device=input_ids.device)
this_peer_finished = False
while True:
if synced_gpus:
this_peer_finished_flag = torch.tensor(0.0 if this_peer_finished else 1.0).to(input_ids.device)
dist.all_reduce(this_peer_finished_flag, op=dist.ReduceOp.SUM)
if this_peer_finished_flag.item() == 0.0:
break
model_inputs = self.prepare_inputs_for_generation(input_ids, **model_kwargs)
outputs = self(
**model_inputs,
return_dict=True,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
)
if synced_gpus and this_peer_finished:
continue
next_token_logits = outputs.logits[:, -1, :]
next_token_scores = logits_processor(input_ids, next_token_logits)
next_token_scores = logits_warper(input_ids, next_token_scores)
if return_dict_in_generate:
if output_scores:
scores += (next_token_scores,)
if output_attentions:
decoder_attentions += (
(outputs.decoder_attentions,) if self.config.is_encoder_decoder else (outputs.attentions,)
)
if self.config.is_encoder_decoder:
cross_attentions += (outputs.cross_attentions,)
if output_hidden_states:
decoder_hidden_states += (
(outputs.decoder_hidden_states,)
if self.config.is_encoder_decoder
else (outputs.hidden_states,)
)
probs = nn.functional.softmax(next_token_scores, dim=-1)
next_tokens = torch.multinomial(probs, num_samples=1).squeeze(1)
if eos_token_id is not None:
if pad_token_id is None:
raise ValueError("If `eos_token_id` is defined, make sure that `pad_token_id` is defined.")
next_tokens = next_tokens * unfinished_sequences + pad_token_id * (1 - unfinished_sequences)
input_ids = torch.cat([input_ids, next_tokens[:, None]], dim=-1)
if streamer is not None:
streamer.put(next_tokens.cpu())
model_kwargs = self._update_model_kwargs_for_generation(
outputs, model_kwargs, is_encoder_decoder=self.config.is_encoder_decoder
)
if eos_token_id_tensor is not None:
unfinished_sequences = unfinished_sequences.mul(
next_tokens.tile(eos_token_id_tensor.shape[0], 1).ne(eos_token_id_tensor.unsqueeze(1)).float().prod(dim=0).int()
)
if unfinished_sequences.max() == 0:
this_peer_finished = True
if stopping_criteria(input_ids, scores):
this_peer_finished = True
if this_peer_finished and not synced_gpus:
break
if streamer is not None:
streamer.end()
if return_dict_in_generate:
if self.config.is_encoder_decoder:
return SampleEncoderDecoderOutput(
sequences=input_ids,
scores=scores,
encoder_attentions=encoder_attentions,
encoder_hidden_states=encoder_hidden_states,
decoder_attentions=decoder_attentions,
cross_attentions=cross_attentions,
decoder_hidden_states=decoder_hidden_states,
)
else:
return SampleDecoderOnlyOutput(
sequences=input_ids,
scores=scores,
attentions=decoder_attentions,
hidden_states=decoder_hidden_states,
)
else:
return input_ids
def beam_search(
self,
input_ids: torch.LongTensor,
beam_scorer: BeamScorer,
logits_processor: Optional[LogitsProcessorList] = None,
stopping_criteria: Optional[StoppingCriteriaList] = None,
max_length: Optional[int] = None,
pad_token_id: Optional[int] = None,
eos_token_id: Optional[Union[int, List[int]]] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
output_scores: Optional[bool] = None,
return_dict_in_generate: Optional[bool] = None,
synced_gpus: bool = False,
**model_kwargs,
) -> Union[BeamSearchOutput, torch.LongTensor]:
r"""
Generates sequences of token ids for models with a language modeling head using **beam search decoding** and
can be used for text-decoder, text-to-text, speech-to-text, and vision-to-text models.
<Tip warning={true}>
In most cases, you do not need to call [`~generation.GenerationMixin.beam_search`] directly. Use generate()
instead. For an overview of generation strategies and code examples, check the [following
guide](../generation_strategies).
</Tip>
Parameters:
input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The sequence used as a prompt for the generation.
beam_scorer (`BeamScorer`):
An derived instance of [`BeamScorer`] that defines how beam hypotheses are constructed, stored and
sorted during generation. For more information, the documentation of [`BeamScorer`] should be read.
logits_processor (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsProcessor`]
used to modify the prediction scores of the language modeling head applied at each generation step.
stopping_criteria (`StoppingCriteriaList`, *optional*):
An instance of [`StoppingCriteriaList`]. List of instances of class derived from [`StoppingCriteria`]
used to tell if the generation loop should stop.
max_length (`int`, *optional*, defaults to 20):
**DEPRECATED**. Use `logits_processor` or `stopping_criteria` directly to cap the number of generated
tokens. The maximum length of the sequence to be generated.
pad_token_id (`int`, *optional*):
The id of the *padding* token.
eos_token_id (`Union[int, List[int]]`, *optional*):
The id of the *end-of-sequence* token. Optionally, use a list to set multiple *end-of-sequence* tokens.
output_attentions (`bool`, *optional*, defaults to `False`):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under
returned tensors for more details.
output_hidden_states (`bool`, *optional*, defaults to `False`):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors
for more details.
output_scores (`bool`, *optional*, defaults to `False`):
Whether or not to return the prediction scores. See `scores` under returned tensors for more details.
return_dict_in_generate (`bool`, *optional*, defaults to `False`):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
synced_gpus (`bool`, *optional*, defaults to `False`):
Whether to continue running the while loop until max_length (needed for ZeRO stage 3)
model_kwargs:
Additional model specific kwargs will be forwarded to the `forward` function of the model. If model is
an encoder-decoder model the kwargs should include `encoder_outputs`.
Return:
[`generation.BeamSearchDecoderOnlyOutput`], [`~generation.BeamSearchEncoderDecoderOutput`] or
`torch.LongTensor`: A `torch.LongTensor` containing the generated tokens (default behaviour) or a
[`~generation.BeamSearchDecoderOnlyOutput`] if `model.config.is_encoder_decoder=False` and
`return_dict_in_generate=True` or a [`~generation.BeamSearchEncoderDecoderOutput`] if
`model.config.is_encoder_decoder=True`.
Examples:
```python
>>> from transformers import (
... AutoTokenizer,
... AutoModelForSeq2SeqLM,
... LogitsProcessorList,
... MinLengthLogitsProcessor,
... BeamSearchScorer,
... )
>>> import torch
>>> tokenizer = AutoTokenizer.from_pretrained("t5-base")
>>> model = AutoModelForSeq2SeqLM.from_pretrained("t5-base")
>>> encoder_input_str = "translate English to German: How old are you?"
>>> encoder_input_ids = tokenizer(encoder_input_str, return_tensors="pt").input_ids
>>> # lets run beam search using 3 beams
>>> num_beams = 3
>>> # define decoder start token ids
>>> input_ids = torch.ones((num_beams, 1), device=model.device, dtype=torch.long)
>>> input_ids = input_ids * model.config.decoder_start_token_id
>>> # add encoder_outputs to model keyword arguments
>>> model_kwargs = {
... "encoder_outputs": model.get_encoder()(
... encoder_input_ids.repeat_interleave(num_beams, dim=0), return_dict=True
... )
... }
>>> # instantiate beam scorer
>>> beam_scorer = BeamSearchScorer(
... batch_size=1,
... num_beams=num_beams,
... device=model.device,
... )
>>> # instantiate logits processors
>>> logits_processor = LogitsProcessorList(
... [
... MinLengthLogitsProcessor(5, eos_token_id=model.config.eos_token_id),
... ]
... )
>>> outputs = model.beam_search(input_ids, beam_scorer, logits_processor=logits_processor, **model_kwargs)
>>> tokenizer.batch_decode(outputs, skip_special_tokens=True)
['Wie alt bist du?']
```"""
logits_processor = logits_processor if logits_processor is not None else LogitsProcessorList()
stopping_criteria = stopping_criteria if stopping_criteria is not None else StoppingCriteriaList()
if max_length is not None:
warnings.warn(
"`max_length` is deprecated in this function, use"
" `stopping_criteria=StoppingCriteriaList(MaxLengthCriteria(max_length=max_length))` instead.",
UserWarning,
)
stopping_criteria = validate_stopping_criteria(stopping_criteria, max_length)
if len(stopping_criteria) == 0:
warnings.warn("You don't have defined any stopping_criteria, this will likely loop forever", UserWarning)
pad_token_id = pad_token_id if pad_token_id is not None else self.generation_config.pad_token_id
eos_token_id = eos_token_id if eos_token_id is not None else self.generation_config.eos_token_id
if isinstance(eos_token_id, int):
eos_token_id = [eos_token_id]
output_scores = output_scores if output_scores is not None else self.generation_config.output_scores
output_attentions = (
output_attentions if output_attentions is not None else self.generation_config.output_attentions
)
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.generation_config.output_hidden_states
)
return_dict_in_generate = (
return_dict_in_generate
if return_dict_in_generate is not None
else self.generation_config.return_dict_in_generate
)
batch_size = len(beam_scorer._beam_hyps)
num_beams = beam_scorer.num_beams
batch_beam_size, cur_len = input_ids.shape
if num_beams * batch_size != batch_beam_size:
raise ValueError(
f"Batch dimension of `input_ids` should be {num_beams * batch_size}, but is {batch_beam_size}."
)
scores = () if (return_dict_in_generate and output_scores) else None
beam_indices = (
tuple(() for _ in range(batch_beam_size)) if (return_dict_in_generate and output_scores) else None
)
decoder_attentions = () if (return_dict_in_generate and output_attentions) else None
cross_attentions = () if (return_dict_in_generate and output_attentions) else None
decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None
if return_dict_in_generate and self.config.is_encoder_decoder:
encoder_attentions = model_kwargs["encoder_outputs"].get("attentions") if output_attentions else None
encoder_hidden_states = (
model_kwargs["encoder_outputs"].get("hidden_states") if output_hidden_states else None
)
beam_scores = torch.zeros((batch_size, num_beams), dtype=torch.float, device=input_ids.device)
beam_scores[:, 1:] = -1e9
beam_scores = beam_scores.view((batch_size * num_beams,))
this_peer_finished = False
while True:
if synced_gpus:
this_peer_finished_flag = torch.tensor(0.0 if this_peer_finished else 1.0).to(input_ids.device)
dist.all_reduce(this_peer_finished_flag, op=dist.ReduceOp.SUM)
if this_peer_finished_flag.item() == 0.0:
break
model_inputs = self.prepare_inputs_for_generation(input_ids, **model_kwargs)
outputs = self(
**model_inputs,
return_dict=True,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
)
if synced_gpus and this_peer_finished:
cur_len = cur_len + 1
continue
next_token_logits = outputs.logits[:, -1, :]
next_token_logits = self.adjust_logits_during_generation(next_token_logits, cur_len=cur_len)
next_token_scores = nn.functional.log_softmax(
next_token_logits, dim=-1
)
next_token_scores_processed = logits_processor(input_ids, next_token_scores)
next_token_scores = next_token_scores_processed + beam_scores[:, None].expand_as(next_token_scores)
if return_dict_in_generate:
if output_scores:
scores += (next_token_scores_processed,)
if output_attentions:
decoder_attentions += (
(outputs.decoder_attentions,) if self.config.is_encoder_decoder else (outputs.attentions,)
)
if self.config.is_encoder_decoder:
cross_attentions += (outputs.cross_attentions,)
if output_hidden_states:
decoder_hidden_states += (
(outputs.decoder_hidden_states,)
if self.config.is_encoder_decoder
else (outputs.hidden_states,)
)
vocab_size = next_token_scores.shape[-1]
next_token_scores = next_token_scores.view(batch_size, num_beams * vocab_size)
next_token_scores, next_tokens = torch.topk(
next_token_scores, 2 * num_beams, dim=1, largest=True, sorted=True
)
next_indices = torch.div(next_tokens, vocab_size, rounding_mode="floor")
next_tokens = next_tokens % vocab_size
beam_outputs = beam_scorer.process(
input_ids,
next_token_scores,
next_tokens,
next_indices,
pad_token_id=pad_token_id,
eos_token_id=eos_token_id,
beam_indices=beam_indices,
)
beam_scores = beam_outputs["next_beam_scores"]
beam_next_tokens = beam_outputs["next_beam_tokens"]
beam_idx = beam_outputs["next_beam_indices"]
input_ids = torch.cat([input_ids[beam_idx, :], beam_next_tokens.unsqueeze(-1)], dim=-1)
model_kwargs = self._update_model_kwargs_for_generation(
outputs, model_kwargs, is_encoder_decoder=self.config.is_encoder_decoder
)
if model_kwargs["past_key_values"] is not None:
model_kwargs["past_key_values"] = self._reorder_cache(model_kwargs["past_key_values"], beam_idx)
if return_dict_in_generate and output_scores:
beam_indices = tuple((beam_indices[beam_idx[i]] + (beam_idx[i],) for i in range(len(beam_indices))))
cur_len = cur_len + 1
if beam_scorer.is_done or stopping_criteria(input_ids, scores):
if not synced_gpus:
break
else:
this_peer_finished = True
sequence_outputs = beam_scorer.finalize(
input_ids,
beam_scores,
next_tokens,
next_indices,
pad_token_id=pad_token_id,
eos_token_id=eos_token_id,
max_length=stopping_criteria.max_length,
beam_indices=beam_indices,
)
if return_dict_in_generate:
if not output_scores:
sequence_outputs["sequence_scores"] = None
if self.config.is_encoder_decoder:
return BeamSearchEncoderDecoderOutput(
sequences=sequence_outputs["sequences"],
sequences_scores=sequence_outputs["sequence_scores"],
scores=scores,
beam_indices=sequence_outputs["beam_indices"],
encoder_attentions=encoder_attentions,
encoder_hidden_states=encoder_hidden_states,
decoder_attentions=decoder_attentions,
cross_attentions=cross_attentions,
decoder_hidden_states=decoder_hidden_states,
)
else:
return BeamSearchDecoderOnlyOutput(
sequences=sequence_outputs["sequences"],
sequences_scores=sequence_outputs["sequence_scores"],
scores=scores,
beam_indices=sequence_outputs["beam_indices"],
attentions=decoder_attentions,
hidden_states=decoder_hidden_states,
)
else:
return sequence_outputs["sequences"]
def beam_sample(
self,
input_ids: torch.LongTensor,
beam_scorer: BeamScorer,
logits_processor: Optional[LogitsProcessorList] = None,
stopping_criteria: Optional[StoppingCriteriaList] = None,
logits_warper: Optional[LogitsProcessorList] = None,
max_length: Optional[int] = None,
pad_token_id: Optional[int] = None,
eos_token_id: Optional[Union[int, List[int]]] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
output_scores: Optional[bool] = None,
return_dict_in_generate: Optional[bool] = None,
synced_gpus: bool = False,
**model_kwargs,
) -> Union[BeamSampleOutput, torch.LongTensor]:
r"""
Generates sequences of token ids for models with a language modeling head using **beam search multinomial
sampling** and can be used for text-decoder, text-to-text, speech-to-text, and vision-to-text models.
<Tip warning={true}>
In most cases, you do not need to call [`~generation.GenerationMixin.beam_sample`] directly. Use generate()
instead. For an overview of generation strategies and code examples, check the [following
guide](../generation_strategies).
</Tip>
Parameters:
input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The sequence used as a prompt for the generation.
beam_scorer (`BeamScorer`):
A derived instance of [`BeamScorer`] that defines how beam hypotheses are constructed, stored and
sorted during generation. For more information, the documentation of [`BeamScorer`] should be read.
logits_processor (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsProcessor`]
used to modify the prediction scores of the language modeling head applied at each generation step.
stopping_criteria (`StoppingCriteriaList`, *optional*):
An instance of [`StoppingCriteriaList`]. List of instances of class derived from [`StoppingCriteria`]
used to tell if the generation loop should stop.
logits_warper (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsWarper`] used
to warp the prediction score distribution of the language modeling head applied before multinomial
sampling at each generation step.
max_length (`int`, *optional*, defaults to 20):
**DEPRECATED**. Use `logits_processor` or `stopping_criteria` directly to cap the number of generated
tokens. The maximum length of the sequence to be generated.
pad_token_id (`int`, *optional*):
The id of the *padding* token.
eos_token_id (`Union[int, List[int]]`, *optional*):
The id of the *end-of-sequence* token. Optionally, use a list to set multiple *end-of-sequence* tokens.
output_attentions (`bool`, *optional*, defaults to `False`):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under
returned tensors for more details.
output_hidden_states (`bool`, *optional*, defaults to `False`):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors
for more details.
output_scores (`bool`, *optional*, defaults to `False`):
Whether or not to return the prediction scores. See `scores` under returned tensors for more details.
return_dict_in_generate (`bool`, *optional*, defaults to `False`):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
synced_gpus (`bool`, *optional*, defaults to `False`):
Whether to continue running the while loop until max_length (needed for ZeRO stage 3)
model_kwargs:
Additional model specific kwargs will be forwarded to the `forward` function of the model. If model is
an encoder-decoder model the kwargs should include `encoder_outputs`.
Return:
[`~generation.BeamSampleDecoderOnlyOutput`], [`~generation.BeamSampleEncoderDecoderOutput`] or
`torch.LongTensor`: A `torch.LongTensor` containing the generated tokens (default behaviour) or a
[`~generation.BeamSampleDecoderOnlyOutput`] if `model.config.is_encoder_decoder=False` and
`return_dict_in_generate=True` or a [`~generation.BeamSampleEncoderDecoderOutput`] if
`model.config.is_encoder_decoder=True`.
Examples:
```python
>>> from transformers import (
... AutoTokenizer,
... AutoModelForSeq2SeqLM,
... LogitsProcessorList,
... MinLengthLogitsProcessor,
... TopKLogitsWarper,
... TemperatureLogitsWarper,
... BeamSearchScorer,
... )
>>> import torch
>>> tokenizer = AutoTokenizer.from_pretrained("t5-base")
>>> model = AutoModelForSeq2SeqLM.from_pretrained("t5-base")
>>> encoder_input_str = "translate English to German: How old are you?"
>>> encoder_input_ids = tokenizer(encoder_input_str, return_tensors="pt").input_ids
>>> # lets run beam search using 3 beams
>>> num_beams = 3
>>> # define decoder start token ids
>>> input_ids = torch.ones((num_beams, 1), device=model.device, dtype=torch.long)
>>> input_ids = input_ids * model.config.decoder_start_token_id
>>> # add encoder_outputs to model keyword arguments
>>> model_kwargs = {
... "encoder_outputs": model.get_encoder()(
... encoder_input_ids.repeat_interleave(num_beams, dim=0), return_dict=True
... )
... }
>>> # instantiate beam scorer
>>> beam_scorer = BeamSearchScorer(
... batch_size=1,
... max_length=model.config.max_length,
... num_beams=num_beams,
... device=model.device,
... )
>>> # instantiate logits processors
>>> logits_processor = LogitsProcessorList(
... [MinLengthLogitsProcessor(5, eos_token_id=model.config.eos_token_id)]
... )
>>> # instantiate logits processors
>>> logits_warper = LogitsProcessorList(
... [
... TopKLogitsWarper(50),
... TemperatureLogitsWarper(0.7),
... ]
... )
>>> outputs = model.beam_sample(
... input_ids, beam_scorer, logits_processor=logits_processor, logits_warper=logits_warper, **model_kwargs
... )
>>> tokenizer.batch_decode(outputs, skip_special_tokens=True)
['Wie alt bist du?']
```"""
logits_processor = logits_processor if logits_processor is not None else LogitsProcessorList()
stopping_criteria = stopping_criteria if stopping_criteria is not None else StoppingCriteriaList()
if max_length is not None:
warnings.warn(
"`max_length` is deprecated in this function, use"
" `stopping_criteria=StoppingCriteriaList(MaxLengthCriteria(max_length=max_length))` instead.",
UserWarning,
)
stopping_criteria = validate_stopping_criteria(stopping_criteria, max_length)
pad_token_id = pad_token_id if pad_token_id is not None else self.generation_config.pad_token_id
eos_token_id = eos_token_id if eos_token_id is not None else self.generation_config.eos_token_id
if isinstance(eos_token_id, int):
eos_token_id = [eos_token_id]
output_scores = output_scores if output_scores is not None else self.generation_config.output_scores
output_attentions = (
output_attentions if output_attentions is not None else self.generation_config.output_attentions
)
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.generation_config.output_hidden_states
)
return_dict_in_generate = (
return_dict_in_generate
if return_dict_in_generate is not None
else self.generation_config.return_dict_in_generate
)
batch_size = len(beam_scorer._beam_hyps)
num_beams = beam_scorer.num_beams
batch_beam_size, cur_len = input_ids.shape
scores = () if (return_dict_in_generate and output_scores) else None
beam_indices = (
tuple(() for _ in range(batch_beam_size)) if (return_dict_in_generate and output_scores) else None
)
decoder_attentions = () if (return_dict_in_generate and output_attentions) else None
cross_attentions = () if (return_dict_in_generate and output_attentions) else None
decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None
if return_dict_in_generate and self.config.is_encoder_decoder:
encoder_attentions = model_kwargs["encoder_outputs"].get("attentions") if output_attentions else None
encoder_hidden_states = (
model_kwargs["encoder_outputs"].get("hidden_states") if output_hidden_states else None
)
beam_scores = torch.zeros((batch_size, num_beams), dtype=torch.float, device=input_ids.device)
beam_scores = beam_scores.view((batch_size * num_beams,))
this_peer_finished = False
while True:
if synced_gpus:
this_peer_finished_flag = torch.tensor(0.0 if this_peer_finished else 1.0).to(input_ids.device)
dist.all_reduce(this_peer_finished_flag, op=dist.ReduceOp.SUM)
if this_peer_finished_flag.item() == 0.0:
break
model_inputs = self.prepare_inputs_for_generation(input_ids, **model_kwargs)
outputs = self(
**model_inputs,
return_dict=True,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
)
if synced_gpus and this_peer_finished:
cur_len = cur_len + 1
continue
next_token_logits = outputs.logits[:, -1, :]
next_token_logits = self.adjust_logits_during_generation(next_token_logits, cur_len=cur_len)
next_token_scores = nn.functional.log_softmax(
next_token_logits, dim=-1
)
next_token_scores_processed = logits_processor(input_ids, next_token_scores)
next_token_scores = next_token_scores_processed + beam_scores[:, None].expand_as(next_token_scores)
next_token_scores = logits_warper(input_ids, next_token_scores)
if return_dict_in_generate:
if output_scores:
scores += (logits_warper(input_ids, next_token_scores_processed),)
if output_attentions:
decoder_attentions += (
(outputs.decoder_attentions,) if self.config.is_encoder_decoder else (outputs.attentions,)
)
if self.config.is_encoder_decoder:
cross_attentions += (outputs.cross_attentions,)
if output_hidden_states:
decoder_hidden_states += (
(outputs.decoder_hidden_states,)
if self.config.is_encoder_decoder
else (outputs.hidden_states,)
)
vocab_size = next_token_scores.shape[-1]
next_token_scores = next_token_scores.view(batch_size, num_beams * vocab_size)
probs = nn.functional.softmax(next_token_scores, dim=-1)
next_tokens = torch.multinomial(probs, num_samples=2 * num_beams)
next_token_scores = torch.gather(next_token_scores, -1, next_tokens)
next_token_scores, _indices = torch.sort(next_token_scores, descending=True, dim=1)
next_tokens = torch.gather(next_tokens, -1, _indices)
next_indices = torch.div(next_tokens, vocab_size, rounding_mode="floor")
next_tokens = next_tokens % vocab_size
beam_outputs = beam_scorer.process(
input_ids,
next_token_scores,
next_tokens,
next_indices,
pad_token_id=pad_token_id,
eos_token_id=eos_token_id,
beam_indices=beam_indices,
)
beam_scores = beam_outputs["next_beam_scores"]
beam_next_tokens = beam_outputs["next_beam_tokens"]
beam_idx = beam_outputs["next_beam_indices"]
input_ids = torch.cat([input_ids[beam_idx, :], beam_next_tokens.unsqueeze(-1)], dim=-1)
model_kwargs = self._update_model_kwargs_for_generation(
outputs, model_kwargs, is_encoder_decoder=self.config.is_encoder_decoder
)
if model_kwargs["past_key_values"] is not None:
model_kwargs["past_key_values"] = self._reorder_cache(model_kwargs["past_key_values"], beam_idx)
if return_dict_in_generate and output_scores:
beam_indices = tuple((beam_indices[beam_idx[i]] + (beam_idx[i],) for i in range(len(beam_indices))))
cur_len = cur_len + 1
if beam_scorer.is_done or stopping_criteria(input_ids, scores):
if not synced_gpus:
break
else:
this_peer_finished = True
sequence_outputs = beam_scorer.finalize(
input_ids,
beam_scores,
next_tokens,
next_indices,
pad_token_id=pad_token_id,
eos_token_id=eos_token_id,
max_length=stopping_criteria.max_length,
beam_indices=beam_indices,
)
if return_dict_in_generate:
if not output_scores:
sequence_outputs["sequence_scores"] = None
if self.config.is_encoder_decoder:
return BeamSampleEncoderDecoderOutput(
sequences=sequence_outputs["sequences"],
sequences_scores=sequence_outputs["sequence_scores"],
scores=scores,
beam_indices=sequence_outputs["beam_indices"],
encoder_attentions=encoder_attentions,
encoder_hidden_states=encoder_hidden_states,
decoder_attentions=decoder_attentions,
cross_attentions=cross_attentions,
decoder_hidden_states=decoder_hidden_states,
)
else:
return BeamSampleDecoderOnlyOutput(
sequences=sequence_outputs["sequences"],
sequences_scores=sequence_outputs["sequence_scores"],
scores=scores,
beam_indices=sequence_outputs["beam_indices"],
attentions=decoder_attentions,
hidden_states=decoder_hidden_states,
)
else:
return sequence_outputs["sequences"]
def group_beam_search(
self,
input_ids: torch.LongTensor,
beam_scorer: BeamScorer,
logits_processor: Optional[LogitsProcessorList] = None,
stopping_criteria: Optional[StoppingCriteriaList] = None,
max_length: Optional[int] = None,
pad_token_id: Optional[int] = None,
eos_token_id: Optional[Union[int, List[int]]] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
output_scores: Optional[bool] = None,
return_dict_in_generate: Optional[bool] = None,
synced_gpus: bool = False,
**model_kwargs,
):
r"""
Generates sequences of token ids for models with a language modeling head using **diverse beam search
decoding** and can be used for text-decoder, text-to-text, speech-to-text, and vision-to-text models.
<Tip warning={true}>
In most cases, you do not need to call [`~generation.GenerationMixin.group_beam_search`] directly. Use
generate() instead. For an overview of generation strategies and code examples, check the [following
guide](../generation_strategies).
</Tip>
Parameters:
input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The sequence used as a prompt for the generation.
beam_scorer (`BeamScorer`):
An derived instance of [`BeamScorer`] that defines how beam hypotheses are constructed, stored and
sorted during generation. For more information, the documentation of [`BeamScorer`] should be read.
logits_processor (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsProcessor`]
used to modify the prediction scores of the language modeling head applied at each generation step.
stopping_criteria (`StoppingCriteriaList`, *optional*):
An instance of [`StoppingCriteriaList`]. List of instances of class derived from [`StoppingCriteria`]
used to tell if the generation loop should stop.
max_length (`int`, *optional*, defaults to 20):
**DEPRECATED**. Use `logits_processor` or `stopping_criteria` directly to cap the number of generated
tokens. The maximum length of the sequence to be generated.
pad_token_id (`int`, *optional*):
The id of the *padding* token.
eos_token_id (`Union[int, List[int]]`, *optional*):
The id of the *end-of-sequence* token. Optionally, use a list to set multiple *end-of-sequence* tokens.
output_attentions (`bool`, *optional*, defaults to `False`):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under
returned tensors for more details.
output_hidden_states (`bool`, *optional*, defaults to `False`):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors
for more details.
output_scores (`bool`, *optional*, defaults to `False`):
Whether or not to return the prediction scores. See `scores` under returned tensors for more details.
return_dict_in_generate (`bool`, *optional*, defaults to `False`):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
synced_gpus (`bool`, *optional*, defaults to `False`):
Whether to continue running the while loop until max_length (needed for ZeRO stage 3)
model_kwargs:
Additional model specific kwargs that will be forwarded to the `forward` function of the model. If
model is an encoder-decoder model the kwargs should include `encoder_outputs`.
Return:
[`~generation.BeamSearchDecoderOnlyOutput`], [`~generation.BeamSearchEncoderDecoderOutput`] or
`torch.LongTensor`: A `torch.LongTensor` containing the generated tokens (default behaviour) or a
[`~generation.BeamSearchDecoderOnlyOutput`] if [`~generation.BeamSearchDecoderOnlyOutput`] if
`model.config.is_encoder_decoder=False` and `return_dict_in_generate=True` or a
[`~generation.BeamSearchEncoderDecoderOutput`] if `model.config.is_encoder_decoder=True`.
Examples:
```python
>>> from transformers import (
... AutoTokenizer,
... AutoModelForSeq2SeqLM,
... LogitsProcessorList,
... MinLengthLogitsProcessor,
... HammingDiversityLogitsProcessor,
... BeamSearchScorer,
... )
>>> import torch
>>> tokenizer = AutoTokenizer.from_pretrained("t5-base")
>>> model = AutoModelForSeq2SeqLM.from_pretrained("t5-base")
>>> encoder_input_str = "translate English to German: How old are you?"
>>> encoder_input_ids = tokenizer(encoder_input_str, return_tensors="pt").input_ids
>>> # lets run diverse beam search using 6 beams
>>> num_beams = 6
>>> # define decoder start token ids
>>> input_ids = torch.ones((num_beams, 1), device=model.device, dtype=torch.long)
>>> input_ids = input_ids * model.config.decoder_start_token_id
>>> # add encoder_outputs to model keyword arguments
>>> model_kwargs = {
... "encoder_outputs": model.get_encoder()(
... encoder_input_ids.repeat_interleave(num_beams, dim=0), return_dict=True
... )
... }
>>> # instantiate beam scorer
>>> beam_scorer = BeamSearchScorer(
... batch_size=1,
... max_length=model.config.max_length,
... num_beams=num_beams,
... device=model.device,
... num_beam_groups=3,
... )
>>> # instantiate logits processors
>>> logits_processor = LogitsProcessorList(
... [
... HammingDiversityLogitsProcessor(5.5, num_beams=6, num_beam_groups=3),
... MinLengthLogitsProcessor(5, eos_token_id=model.config.eos_token_id),
... ]
... )
>>> outputs = model.group_beam_search(
... input_ids, beam_scorer, logits_processor=logits_processor, **model_kwargs
... )
>>> tokenizer.batch_decode(outputs, skip_special_tokens=True)
['Wie alt bist du?']
```"""
logits_processor = logits_processor if logits_processor is not None else LogitsProcessorList()
stopping_criteria = stopping_criteria if stopping_criteria is not None else StoppingCriteriaList()
if max_length is not None:
warnings.warn(
"`max_length` is deprecated in this function, use"
" `stopping_criteria=StoppingCriteriaList(MaxLengthCriteria(max_length=max_length))` instead.",
UserWarning,
)
stopping_criteria = validate_stopping_criteria(stopping_criteria, max_length)
pad_token_id = pad_token_id if pad_token_id is not None else self.generation_config.pad_token_id
eos_token_id = eos_token_id if eos_token_id is not None else self.generation_config.eos_token_id
if isinstance(eos_token_id, int):
eos_token_id = [eos_token_id]
output_scores = output_scores if output_scores is not None else self.generation_config.output_scores
output_attentions = (
output_attentions if output_attentions is not None else self.generation_config.output_attentions
)
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.generation_config.output_hidden_states
)
return_dict_in_generate = (
return_dict_in_generate
if return_dict_in_generate is not None
else self.generation_config.return_dict_in_generate
)
batch_size = len(beam_scorer._beam_hyps)
num_beams = beam_scorer.num_beams
num_beam_groups = beam_scorer.num_beam_groups
num_sub_beams = num_beams // num_beam_groups
device = input_ids.device
batch_beam_size, cur_len = input_ids.shape
if return_dict_in_generate and output_scores:
beam_indices = [tuple(() for _ in range(num_sub_beams * batch_size)) for _ in range(num_beam_groups)]
else:
beam_indices = None
if num_beams * batch_size != batch_beam_size:
raise ValueError(
f"Batch dimension of `input_ids` should be {num_beams * batch_size}, but is {batch_beam_size}."
)
scores = () if (return_dict_in_generate and output_scores) else None
decoder_attentions = () if (return_dict_in_generate and output_attentions) else None
cross_attentions = () if (return_dict_in_generate and output_attentions) else None
decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None
if return_dict_in_generate and self.config.is_encoder_decoder:
encoder_attentions = model_kwargs["encoder_outputs"].get("attentions") if output_attentions else None
encoder_hidden_states = (
model_kwargs["encoder_outputs"].get("hidden_states") if output_hidden_states else None
)
beam_scores = torch.full((batch_size, num_beams), -1e9, dtype=torch.float, device=device)
beam_scores[:, ::num_sub_beams] = 0
beam_scores = beam_scores.view((batch_size * num_beams,))
this_peer_finished = False
while True:
if synced_gpus:
this_peer_finished_flag = torch.tensor(0.0 if this_peer_finished else 1.0).to(input_ids.device)
dist.all_reduce(this_peer_finished_flag, op=dist.ReduceOp.SUM)
if this_peer_finished_flag.item() == 0.0:
break
current_tokens = torch.zeros(batch_size * num_beams, dtype=input_ids.dtype, device=device)
reordering_indices = torch.zeros(batch_size * num_beams, dtype=torch.long, device=device)
model_inputs = self.prepare_inputs_for_generation(input_ids, **model_kwargs)
outputs = self(
**model_inputs,
return_dict=True,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
)
if synced_gpus and this_peer_finished:
cur_len = cur_len + 1
continue
if output_scores:
processed_score = torch.zeros_like(outputs.logits[:, -1, :])
for beam_group_idx in range(num_beam_groups):
group_start_idx = beam_group_idx * num_sub_beams
group_end_idx = min(group_start_idx + num_sub_beams, num_beams)
group_size = group_end_idx - group_start_idx
batch_group_indices = []
for batch_idx in range(batch_size):
batch_group_indices.extend(
[batch_idx * num_beams + idx for idx in range(group_start_idx, group_end_idx)]
)
group_input_ids = input_ids[batch_group_indices]
next_token_logits = outputs.logits[batch_group_indices, -1, :]
next_token_logits = self.adjust_logits_during_generation(next_token_logits, cur_len=cur_len)
next_token_scores = nn.functional.log_softmax(
next_token_logits, dim=-1
)
vocab_size = next_token_scores.shape[-1]
next_token_scores_processed = logits_processor(
group_input_ids, next_token_scores, current_tokens=current_tokens, beam_group_idx=beam_group_idx
)
next_token_scores = next_token_scores_processed + beam_scores[batch_group_indices].unsqueeze(-1)
next_token_scores = next_token_scores.expand_as(next_token_scores_processed)
if output_scores:
processed_score[batch_group_indices] = next_token_scores_processed
next_token_scores = next_token_scores.view(batch_size, group_size * vocab_size)
next_token_scores, next_tokens = torch.topk(
next_token_scores, 2 * group_size, dim=1, largest=True, sorted=True
)
next_indices = torch.div(next_tokens, vocab_size, rounding_mode="floor")
next_tokens = next_tokens % vocab_size
process_beam_indices = sum(beam_indices, ()) if beam_indices is not None else None
beam_outputs = beam_scorer.process(
group_input_ids,
next_token_scores,
next_tokens,
next_indices,
pad_token_id=pad_token_id,
eos_token_id=eos_token_id,
beam_indices=process_beam_indices,
)
beam_scores[batch_group_indices] = beam_outputs["next_beam_scores"]
beam_next_tokens = beam_outputs["next_beam_tokens"]
beam_idx = beam_outputs["next_beam_indices"]
if return_dict_in_generate and output_scores:
beam_indices[beam_group_idx] = tuple(
beam_indices[beam_group_idx][beam_idx[i]] + (beam_idx[i],) for i in range(len(beam_indices[0]))
)
input_ids[batch_group_indices] = group_input_ids[beam_idx]
group_input_ids = torch.cat([group_input_ids[beam_idx, :], beam_next_tokens.unsqueeze(-1)], dim=-1)
current_tokens[batch_group_indices] = group_input_ids[:, -1]
reordering_indices[batch_group_indices] = (
num_beams * torch.div(beam_idx, group_size, rounding_mode="floor")
+ group_start_idx
+ (beam_idx % group_size)
)
if return_dict_in_generate:
if output_scores:
scores += (processed_score,)
if output_attentions:
decoder_attentions += (
(outputs.decoder_attentions,) if self.config.is_encoder_decoder else (outputs.attentions,)
)
if self.config.is_encoder_decoder:
cross_attentions += (outputs.cross_attentions,)
if output_hidden_states:
decoder_hidden_states += (
(outputs.decoder_hidden_states,)
if self.config.is_encoder_decoder
else (outputs.hidden_states,)
)
input_ids = torch.cat([input_ids, current_tokens.unsqueeze(-1)], dim=-1)
model_kwargs = self._update_model_kwargs_for_generation(
outputs, model_kwargs, is_encoder_decoder=self.config.is_encoder_decoder
)
if model_kwargs["past_key_values"] is not None:
model_kwargs["past_key_values"] = self._reorder_cache(
model_kwargs["past_key_values"], reordering_indices
)
cur_len = cur_len + 1
if beam_scorer.is_done or stopping_criteria(input_ids, scores):
if not synced_gpus:
break
else:
this_peer_finished = True
final_beam_indices = sum(beam_indices, ()) if beam_indices is not None else None
sequence_outputs = beam_scorer.finalize(
input_ids,
beam_scores,
next_tokens,
next_indices,
pad_token_id=pad_token_id,
eos_token_id=eos_token_id,
max_length=stopping_criteria.max_length,
beam_indices=final_beam_indices,
)
if return_dict_in_generate:
if not output_scores:
sequence_outputs["sequence_scores"] = None
if self.config.is_encoder_decoder:
return BeamSearchEncoderDecoderOutput(
sequences=sequence_outputs["sequences"],
sequences_scores=sequence_outputs["sequence_scores"],
scores=scores,
beam_indices=sequence_outputs["beam_indices"],
encoder_attentions=encoder_attentions,
encoder_hidden_states=encoder_hidden_states,
decoder_attentions=decoder_attentions,
cross_attentions=cross_attentions,
decoder_hidden_states=decoder_hidden_states,
)
else:
return BeamSearchDecoderOnlyOutput(
sequences=sequence_outputs["sequences"],
sequences_scores=sequence_outputs["sequence_scores"],
scores=scores,
beam_indices=sequence_outputs["beam_indices"],
attentions=decoder_attentions,
hidden_states=decoder_hidden_states,
)
else:
return sequence_outputs["sequences"]
def constrained_beam_search(
self,
input_ids: torch.LongTensor,
constrained_beam_scorer: ConstrainedBeamSearchScorer,
logits_processor: Optional[LogitsProcessorList] = None,
stopping_criteria: Optional[StoppingCriteriaList] = None,
max_length: Optional[int] = None,
pad_token_id: Optional[int] = None,
eos_token_id: Optional[Union[int, List[int]]] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
output_scores: Optional[bool] = None,
return_dict_in_generate: Optional[bool] = None,
synced_gpus: Optional[bool] = None,
**model_kwargs,
) -> Union[BeamSearchOutput, torch.LongTensor]:
r"""
Generates sequences of token ids for models with a language modeling head using **constrained beam search
decoding** and can be used for text-decoder, text-to-text, speech-to-text, and vision-to-text models.
<Tip warning={true}>
In most cases, you do not need to call [`~generation.GenerationMixin.constrained_beam_search`] directly. Use
generate() instead. For an overview of generation strategies and code examples, check the [following
guide](../generation_strategies).
</Tip>
Parameters:
input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The sequence used as a prompt for the generation.
constrained_beam_scorer (`ConstrainedBeamSearchScorer`):
A derived instance of [`BeamScorer`] that defines how beam hypotheses are constructed, stored and
sorted during generation, while satisfying a list of positive constraints. For more information, the
documentation of [`ConstrainedBeamSearchScorer`] should be read.
logits_processor (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsProcessor`]
used to modify the prediction scores of the language modeling head applied at each generation step.
stopping_criteria (`StoppingCriteriaList`, *optional*):
An instance of [`StoppingCriteriaList`]. List of instances of class derived from [`StoppingCriteria`]
used to tell if the generation loop should stop.
logits_warper (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsWarper`] used
to warp the prediction score distribution of the language modeling head applied before multinomial
sampling at each generation step.
max_length (`int`, *optional*, defaults to 20):
**DEPRECATED**. Use `logits_processor` or `stopping_criteria` directly to cap the number of generated
tokens. The maximum length of the sequence to be generated.
pad_token_id (`int`, *optional*):
The id of the *padding* token.
eos_token_id (`Union[int, List[int]]`, *optional*):
The id of the *end-of-sequence* token. Optionally, use a list to set multiple *end-of-sequence* tokens.
output_attentions (`bool`, *optional*, defaults to `False`):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under
returned tensors for more details.
output_hidden_states (`bool`, *optional*, defaults to `False`):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors
for more details.
output_scores (`bool`, *optional*, defaults to `False`):
Whether or not to return the prediction scores. See `scores` under returned tensors for more details.
return_dict_in_generate (`bool`, *optional*, defaults to `False`):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
synced_gpus (`bool`, *optional*, defaults to `False`):
Whether to continue running the while loop until max_length (needed for ZeRO stage 3)
model_kwargs:
Additional model specific kwargs will be forwarded to the `forward` function of the model. If model is
an encoder-decoder model the kwargs should include `encoder_outputs`.
Return:
[`generation.BeamSearchDecoderOnlyOutput`], [`~generation.BeamSearchEncoderDecoderOutput`] or
`torch.LongTensor`: A `torch.LongTensor` containing the generated tokens (default behaviour) or a
[`~generation.BeamSearchDecoderOnlyOutput`] if `model.config.is_encoder_decoder=False` and
`return_dict_in_generate=True` or a [`~generation.BeamSearchEncoderDecoderOutput`] if
`model.config.is_encoder_decoder=True`.
Examples:
```python
>>> from transformers import (
... AutoTokenizer,
... AutoModelForSeq2SeqLM,
... LogitsProcessorList,
... MinLengthLogitsProcessor,
... ConstrainedBeamSearchScorer,
... PhrasalConstraint,
... )
>>> import torch
>>> tokenizer = AutoTokenizer.from_pretrained("t5-base")
>>> model = AutoModelForSeq2SeqLM.from_pretrained("t5-base")
>>> encoder_input_str = "translate English to German: How old are you?"
>>> encoder_input_ids = tokenizer(encoder_input_str, return_tensors="pt").input_ids
>>> # lets run beam search using 3 beams
>>> num_beams = 3
>>> # define decoder start token ids
>>> input_ids = torch.ones((num_beams, 1), device=model.device, dtype=torch.long)
>>> input_ids = input_ids * model.config.decoder_start_token_id
>>> # add encoder_outputs to model keyword arguments
>>> model_kwargs = {
... "encoder_outputs": model.get_encoder()(
... encoder_input_ids.repeat_interleave(num_beams, dim=0), return_dict=True
... )
... }
>>> constraint_str = "Sie"
>>> constraint_token_ids = tokenizer.encode(constraint_str)[:-1] # slice to remove eos token
>>> constraints = [PhrasalConstraint(token_ids=constraint_token_ids)]
>>> # instantiate beam scorer
>>> beam_scorer = ConstrainedBeamSearchScorer(
... batch_size=1, num_beams=num_beams, device=model.device, constraints=constraints
... )
>>> # instantiate logits processors
>>> logits_processor = LogitsProcessorList(
... [
... MinLengthLogitsProcessor(5, eos_token_id=model.config.eos_token_id),
... ]
... )
>>> outputs = model.constrained_beam_search(
... input_ids, beam_scorer, constraints=constraints, logits_processor=logits_processor, **model_kwargs
... )
>>> tokenizer.batch_decode(outputs, skip_special_tokens=True)
['Wie alt sind Sie?']
```"""
logits_processor = logits_processor if logits_processor is not None else LogitsProcessorList()
stopping_criteria = stopping_criteria if stopping_criteria is not None else StoppingCriteriaList()
if max_length is not None:
warnings.warn(
"`max_length` is deprecated in this function, use"
" `stopping_criteria=StoppingCriteriaList(MaxLengthCriteria(max_length=max_length))` instead.",
UserWarning,
)
stopping_criteria = validate_stopping_criteria(stopping_criteria, max_length)
if len(stopping_criteria) == 0:
warnings.warn("You don't have defined any stopping_criteria, this will likely loop forever", UserWarning)
pad_token_id = pad_token_id if pad_token_id is not None else self.generation_config.pad_token_id
eos_token_id = eos_token_id if eos_token_id is not None else self.generation_config.eos_token_id
if isinstance(eos_token_id, int):
eos_token_id = [eos_token_id]
output_scores = output_scores if output_scores is not None else self.generation_config.output_scores
output_attentions = (
output_attentions if output_attentions is not None else self.generation_config.output_attentions
)
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.generation_config.output_hidden_states
)
return_dict_in_generate = (
return_dict_in_generate
if return_dict_in_generate is not None
else self.generation_config.return_dict_in_generate
)
scores = () if (return_dict_in_generate and output_scores) else None
decoder_attentions = () if (return_dict_in_generate and output_attentions) else None
cross_attentions = () if (return_dict_in_generate and output_attentions) else None
decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None
if return_dict_in_generate and self.config.is_encoder_decoder:
encoder_attentions = model_kwargs["encoder_outputs"].get("attentions") if output_attentions else None
encoder_hidden_states = (
model_kwargs["encoder_outputs"].get("hidden_states") if output_hidden_states else None
)
batch_size = len(constrained_beam_scorer._beam_hyps)
num_beams = constrained_beam_scorer.num_beams
batch_beam_size, cur_len = input_ids.shape
if num_beams * batch_size != batch_beam_size:
raise ValueError(
f"Batch dimension of `input_ids` should be {num_beams * batch_size}, but is {batch_beam_size}."
)
beam_scores = torch.zeros((batch_size, num_beams), dtype=torch.float, device=input_ids.device)
beam_scores[:, 1:] = -1e9
beam_scores = beam_scores.view((batch_size * num_beams,))
this_peer_finished = False
while True:
if synced_gpus:
this_peer_finished_flag = torch.tensor(0.0 if this_peer_finished else 1.0).to(input_ids.device)
dist.all_reduce(this_peer_finished_flag, op=dist.ReduceOp.SUM)
if this_peer_finished_flag.item() == 0.0:
break
model_inputs = self.prepare_inputs_for_generation(input_ids, **model_kwargs)
outputs = self(
**model_inputs,
return_dict=True,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
)
if synced_gpus and this_peer_finished:
cur_len = cur_len + 1
continue
next_token_logits = outputs.logits[:, -1, :]
next_token_logits = self.adjust_logits_during_generation(next_token_logits, cur_len=cur_len)
next_token_scores = nn.functional.log_softmax(
next_token_logits, dim=-1
)
next_token_scores_processed = logits_processor(input_ids, next_token_scores)
next_token_scores = next_token_scores_processed + beam_scores[:, None].expand_as(next_token_scores)
scores_for_all_vocab = next_token_scores.clone()
if return_dict_in_generate:
if output_scores:
scores += (next_token_scores,)
if output_attentions:
decoder_attentions += (
(outputs.decoder_attentions,) if self.config.is_encoder_decoder else (outputs.attentions,)
)
if self.config.is_encoder_decoder:
cross_attentions += (outputs.cross_attentions,)
if output_hidden_states:
decoder_hidden_states += (
(outputs.decoder_hidden_states,)
if self.config.is_encoder_decoder
else (outputs.hidden_states,)
)
vocab_size = next_token_scores.shape[-1]
next_token_scores = next_token_scores.view(batch_size, num_beams * vocab_size)
next_token_scores, next_tokens = torch.topk(
next_token_scores, 2 * num_beams, dim=1, largest=True, sorted=True
)
next_indices = (next_tokens / vocab_size).long()
next_tokens = next_tokens % vocab_size
beam_outputs = constrained_beam_scorer.process(
input_ids,
next_token_scores,
next_tokens,
next_indices,
scores_for_all_vocab,
pad_token_id=pad_token_id,
eos_token_id=eos_token_id,
)
beam_scores = beam_outputs["next_beam_scores"]
beam_next_tokens = beam_outputs["next_beam_tokens"]
beam_idx = beam_outputs["next_beam_indices"]
input_ids = torch.cat([input_ids[beam_idx, :], beam_next_tokens.unsqueeze(-1)], dim=-1)
model_kwargs = self._update_model_kwargs_for_generation(
outputs, model_kwargs, is_encoder_decoder=self.config.is_encoder_decoder
)
if model_kwargs["past_key_values"] is not None:
model_kwargs["past_key_values"] = self._reorder_cache(model_kwargs["past_key_values"], beam_idx)
cur_len = cur_len + 1
if constrained_beam_scorer.is_done or stopping_criteria(input_ids, scores):
if not synced_gpus:
break
else:
this_peer_finished = True
sequence_outputs = constrained_beam_scorer.finalize(
input_ids,
beam_scores,
next_tokens,
next_indices,
pad_token_id=pad_token_id,
eos_token_id=eos_token_id,
max_length=stopping_criteria.max_length,
)
if return_dict_in_generate:
if not output_scores:
sequence_outputs["sequence_scores"] = None
if self.config.is_encoder_decoder:
return BeamSearchEncoderDecoderOutput(
sequences=sequence_outputs["sequences"],
sequences_scores=sequence_outputs["sequence_scores"],
scores=scores,
encoder_attentions=encoder_attentions,
encoder_hidden_states=encoder_hidden_states,
decoder_attentions=decoder_attentions,
cross_attentions=cross_attentions,
decoder_hidden_states=decoder_hidden_states,
)
else:
return BeamSearchDecoderOnlyOutput(
sequences=sequence_outputs["sequences"],
sequences_scores=sequence_outputs["sequence_scores"],
scores=scores,
attentions=decoder_attentions,
hidden_states=decoder_hidden_states,
)
else:
return sequence_outputs["sequences"]
def assisted_decoding(
self,
input_ids: torch.LongTensor,
assistant_model: "PreTrainedModel",
do_sample: bool = False,
logits_processor: Optional[LogitsProcessorList] = None,
logits_warper: Optional[LogitsProcessorList] = None,
stopping_criteria: Optional[StoppingCriteriaList] = None,
pad_token_id: Optional[int] = None,
eos_token_id: Optional[Union[int, List[int]]] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
output_scores: Optional[bool] = None,
return_dict_in_generate: Optional[bool] = None,
synced_gpus: bool = False,
streamer: Optional["BaseStreamer"] = None,
**model_kwargs,
):
r"""
Generates sequences of token ids for models with a language modeling head using **greedy decoding** or
**sample** (depending on `do_sample`), assisted by a smaller model. Can be used for text-decoder, text-to-text,
speech-to-text, and vision-to-text models.
<Tip warning={true}>
In most cases, you do not need to call [`~generation.GenerationMixin.assisted_decoding`] directly. Use
generate() instead. For an overview of generation strategies and code examples, check the [following
guide](../generation_strategies).
</Tip>
Parameters:
input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
The sequence used as a prompt for the generation.
assistant_model (`PreTrainedModel`, *optional*):
An assistant model that can be used to accelerate generation. The assistant model must have the exact
same tokenizer. The acceleration is achieved when forecasting candidate tokens with the assistent model
is much faster than running generation with the model you're calling generate from. As such, the
assistant model should be much smaller.
do_sample (`bool`, *optional*, defaults to `False`):
Whether or not to use sampling ; use greedy decoding otherwise.
logits_processor (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsProcessor`]
used to modify the prediction scores of the language modeling head applied at each generation step.
logits_warper (`LogitsProcessorList`, *optional*):
An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsWarper`] used
to warp the prediction score distribution of the language modeling head applied before multinomial
sampling at each generation step.
stopping_criteria (`StoppingCriteriaList`, *optional*):
An instance of [`StoppingCriteriaList`]. List of instances of class derived from [`StoppingCriteria`]
used to tell if the generation loop should stop.
pad_token_id (`int`, *optional*):
The id of the *padding* token.
eos_token_id (`Union[int, List[int]]`, *optional*):
The id of the *end-of-sequence* token. Optionally, use a list to set multiple *end-of-sequence* tokens.
output_attentions (`bool`, *optional*, defaults to `False`):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under
returned tensors for more details.
output_hidden_states (`bool`, *optional*, defaults to `False`):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors
for more details.
output_scores (`bool`, *optional*, defaults to `False`):
Whether or not to return the prediction scores. See `scores` under returned tensors for more details.
return_dict_in_generate (`bool`, *optional*, defaults to `False`):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
synced_gpus (`bool`, *optional*, defaults to `False`):
Whether to continue running the while loop until max_length (needed for ZeRO stage 3)
streamer (`BaseStreamer`, *optional*):
Streamer object that will be used to stream the generated sequences. Generated tokens are passed
through `streamer.put(token_ids)` and the streamer is responsible for any further processing.
model_kwargs:
Additional model specific keyword arguments will be forwarded to the `forward` function of the model.
If model is an encoder-decoder model the kwargs should include `encoder_outputs`.
Return:
[`~generation.GreedySearchDecoderOnlyOutput`], [`~generation.GreedySearchEncoderDecoderOutput`] or
`torch.LongTensor`: A `torch.LongTensor` containing the generated tokens (default behaviour) or a
[`~generation.GreedySearchDecoderOnlyOutput`] if `model.config.is_encoder_decoder=False` and
`return_dict_in_generate=True` or a [`~generation.GreedySearchEncoderDecoderOutput`] if
`model.config.is_encoder_decoder=True`.
Examples:
```python
>>> from transformers import (
... AutoTokenizer,
... AutoModelForCausalLM,
... LogitsProcessorList,
... MinLengthLogitsProcessor,
... StoppingCriteriaList,
... MaxLengthCriteria,
... )
>>> tokenizer = AutoTokenizer.from_pretrained("gpt2")
>>> model = AutoModelForCausalLM.from_pretrained("gpt2")
>>> assistant_model = AutoModelForCausalLM.from_pretrained("distilgpt2")
>>> # set pad_token_id to eos_token_id because GPT2 does not have a PAD token
>>> model.generation_config.pad_token_id = model.generation_config.eos_token_id
>>> input_prompt = "It might be possible to"
>>> input_ids = tokenizer(input_prompt, return_tensors="pt").input_ids
>>> # instantiate logits processors
>>> logits_processor = LogitsProcessorList(
... [
... MinLengthLogitsProcessor(10, eos_token_id=model.generation_config.eos_token_id),
... ]
... )
>>> stopping_criteria = StoppingCriteriaList([MaxLengthCriteria(max_length=20)])
>>> outputs = model.assisted_decoding(
... input_ids,
... assistant_model=assistant_model,
... logits_processor=logits_processor,
... stopping_criteria=stopping_criteria,
... )
>>> tokenizer.batch_decode(outputs, skip_special_tokens=True)
["It might be possible to get a better understanding of the nature of the problem, but it's not"]
```"""
if not hasattr(assistant_model, "max_assistant_tokens"):
assistant_model.max_assistant_tokens = 5
logits_processor = logits_processor if logits_processor is not None else LogitsProcessorList()
logits_warper = logits_warper if logits_warper is not None else LogitsProcessorList()
stopping_criteria = stopping_criteria if stopping_criteria is not None else StoppingCriteriaList()
pad_token_id = pad_token_id if pad_token_id is not None else self.generation_config.pad_token_id
eos_token_id = eos_token_id if eos_token_id is not None else self.generation_config.eos_token_id
if eos_token_id is not None and pad_token_id is None:
raise ValueError("If `eos_token_id` is defined, make sure that `pad_token_id` is defined.")
if isinstance(eos_token_id, int):
eos_token_id = [eos_token_id]
eos_token_id_tensor = torch.tensor(eos_token_id).to(input_ids.device) if eos_token_id is not None else None
output_scores = output_scores if output_scores is not None else self.generation_config.output_scores
output_attentions = (
output_attentions if output_attentions is not None else self.generation_config.output_attentions
)
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.generation_config.output_hidden_states
)
return_dict_in_generate = (
return_dict_in_generate
if return_dict_in_generate is not None
else self.generation_config.return_dict_in_generate
)
scores = () if (return_dict_in_generate and output_scores) else None
decoder_attentions = () if (return_dict_in_generate and output_attentions) else None
cross_attentions = () if (return_dict_in_generate and output_attentions) else None
decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None
if return_dict_in_generate and self.config.is_encoder_decoder:
encoder_attentions = model_kwargs["encoder_outputs"].get("attentions") if output_attentions else None
encoder_hidden_states = (
model_kwargs["encoder_outputs"].get("hidden_states") if output_hidden_states else None
)
unfinished_sequences = input_ids.new(input_ids.shape[0]).fill_(1)
max_len = stopping_criteria[0].max_length
this_peer_finished = False
while True:
if synced_gpus:
this_peer_finished_flag = torch.tensor(0.0 if this_peer_finished else 1.0).to(input_ids.device)
dist.all_reduce(this_peer_finished_flag, op=dist.ReduceOp.SUM)
if this_peer_finished_flag.item() == 0.0:
break
cur_len = input_ids.shape[-1]
assistant_kv_indexing = 0 if "bloom" not in assistant_model.__class__.__name__.lower() else 1
candidate_input_ids = input_ids
for _ in range(int(assistant_model.max_assistant_tokens)):
if "assistant_past_key_values" in model_kwargs:
prev_seq_len = model_kwargs["assistant_past_key_values"][0][assistant_kv_indexing].shape[-2]
new_token_len = candidate_input_ids.shape[1] - prev_seq_len
assist_inputs = candidate_input_ids[:, -new_token_len:]
assist_attn = torch.ones_like(candidate_input_ids)
if assistant_model.config.is_encoder_decoder:
assistant_model_outputs = assistant_model(
decoder_input_ids=assist_inputs,
decoder_attention_mask=assist_attn,
past_key_values=model_kwargs["assistant_past_key_values"],
encoder_outputs=model_kwargs["assistant_encoder_outputs"],
)
else:
assistant_model_outputs = assistant_model(
assist_inputs,
attention_mask=assist_attn,
past_key_values=model_kwargs["assistant_past_key_values"],
)
else:
if assistant_model.config.is_encoder_decoder:
assistant_model_outputs = assistant_model(
decoder_input_ids=candidate_input_ids,
encoder_outputs=model_kwargs["assistant_encoder_outputs"],
)
else:
assistant_model_outputs = assistant_model(candidate_input_ids)
model_kwargs["assistant_past_key_values"] = assistant_model_outputs.past_key_values
if len(logits_processor) > 0:
assistant_model_outputs.logits[:, -1, :] = logits_processor(
candidate_input_ids, assistant_model_outputs.logits[:, -1, :]
)
new_token = assistant_model_outputs.logits[:, -1, :].argmax(dim=-1)
candidate_input_ids = torch.cat((candidate_input_ids, new_token[:, None]), dim=-1)
if eos_token_id_tensor is not None:
last_assistant_token_is_eos = new_token.tile(eos_token_id_tensor.shape[0], 1)
last_assistant_token_is_eos = (
~last_assistant_token_is_eos.ne(eos_token_id_tensor.unsqueeze(1)).prod(dim=0).bool()
)
if last_assistant_token_is_eos:
break
else:
last_assistant_token_is_eos = False
candidate_length = candidate_input_ids.shape[1] - input_ids.shape[1]
if "past_key_values" in model_kwargs:
model_attn = torch.ones_like(candidate_input_ids)
model_input_ids = candidate_input_ids[:, -candidate_length - 1 :]
if self.config.is_encoder_decoder:
outputs = self(
decoder_input_ids=model_input_ids,
decoder_attention_mask=model_attn,
past_key_values=model_kwargs["past_key_values"],
encoder_outputs=model_kwargs["encoder_outputs"],
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
)
else:
outputs = self(
model_input_ids,
attention_mask=model_attn,
past_key_values=model_kwargs["past_key_values"],
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
)
else:
if self.config.is_encoder_decoder:
outputs = self(
decoder_input_ids=candidate_input_ids,
encoder_outputs=model_kwargs["encoder_outputs"],
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
)
else:
outputs = self(
candidate_input_ids,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
)
new_logits = outputs.logits[:, -candidate_length - 1 :]
if len(logits_processor) > 0:
for i in range(candidate_length):
new_logits[:, i, :] = logits_processor(candidate_input_ids[:, : cur_len + i], new_logits[:, i, :])
if len(logits_warper) > 0:
for i in range(candidate_length):
new_logits[:, i, :] = logits_warper(candidate_input_ids[:, : cur_len + i], new_logits[:, i, :])
if do_sample:
probs = new_logits[:, -candidate_length - 1 :, :].softmax(dim=-1)
selected_tokens = torch.multinomial(probs[0, :, :], num_samples=1).squeeze(1)[None, :]
else:
selected_tokens = new_logits[:, -candidate_length - 1 :, :].argmax(dim=-1)
candidate_new_tokens = candidate_input_ids[:, -candidate_length:]
n_matches = ((~(candidate_new_tokens == selected_tokens[:, :-1])).cumsum(dim=-1) < 1).sum()
if last_assistant_token_is_eos and n_matches == candidate_length:
n_matches -= 1
n_matches = min(n_matches, max_len - cur_len - 1)
valid_tokens = selected_tokens[:, : n_matches + 1]
input_ids = torch.cat((input_ids, valid_tokens), dim=-1)
if streamer is not None:
streamer.put(valid_tokens.cpu())
new_cur_len = input_ids.shape[-1]
new_cache_size = new_cur_len - 1
outputs.past_key_values = _crop_past_key_values(self, outputs.past_key_values, new_cache_size)
model_kwargs["assistant_past_key_values"] = _crop_past_key_values(
assistant_model, model_kwargs["assistant_past_key_values"], new_cache_size - 1
)
if n_matches == int(assistant_model.max_assistant_tokens):
assistant_model.max_assistant_tokens += 2.0
else:
assistant_model.max_assistant_tokens = max(1.0, assistant_model.max_assistant_tokens - 1.0)
if synced_gpus and this_peer_finished:
continue
if return_dict_in_generate:
if output_scores:
scores += tuple(new_logits[:, i, :] for i in range(n_matches + 1))
if "past_key_values" not in model_kwargs:
added_len = new_cur_len
else:
added_len = n_matches + 1
if output_attentions:
if self.config.is_encoder_decoder:
cross_attentions = _split_model_outputs(
cross_attentions, outputs.cross_attentions, cur_len, added_len
)
decoder_attentions = _split_model_outputs(
decoder_attentions,
outputs.decoder_attentions,
cur_len,
added_len,
is_decoder_attention=True,
)
else:
decoder_attentions = _split_model_outputs(
decoder_attentions,
outputs.attentions,
cur_len,
added_len,
is_decoder_attention=True,
)
if output_hidden_states:
if self.config.is_encoder_decoder:
decoder_hidden_states = _split_model_outputs(
decoder_hidden_states, outputs.decoder_hidden_states, cur_len, added_len
)
else:
decoder_hidden_states = _split_model_outputs(
decoder_hidden_states, outputs.hidden_states, cur_len, added_len
)
model_kwargs = self._update_model_kwargs_for_generation(
outputs, model_kwargs, is_encoder_decoder=self.config.is_encoder_decoder
)
if eos_token_id_tensor is not None:
unfinished_sequences = unfinished_sequences.mul(
input_ids[:, -1]
.tile(eos_token_id_tensor.shape[0], 1)
.ne(eos_token_id_tensor.unsqueeze(1))
.prod(dim=0)
)
if unfinished_sequences.max() == 0:
this_peer_finished = True
if stopping_criteria(input_ids, scores):
this_peer_finished = True
if this_peer_finished and not synced_gpus:
break
if streamer is not None:
streamer.end()
if return_dict_in_generate:
if self.config.is_encoder_decoder:
return GreedySearchEncoderDecoderOutput(
sequences=input_ids,
scores=scores,
encoder_attentions=encoder_attentions,
encoder_hidden_states=encoder_hidden_states,
decoder_attentions=decoder_attentions,
cross_attentions=cross_attentions,
decoder_hidden_states=decoder_hidden_states,
)
else:
return GreedySearchDecoderOnlyOutput(
sequences=input_ids,
scores=scores,
attentions=decoder_attentions,
hidden_states=decoder_hidden_states,
)
else:
return input_ids
def _crop_past_key_values(model, past_key_values, maximum_length):
"""Crops the past key values up to a certain maximum length."""
new_past = []
if model.config.is_encoder_decoder:
for idx in range(len(past_key_values)):
new_past.append(
(
past_key_values[idx][0][:, :, :maximum_length, :],
past_key_values[idx][1][:, :, :maximum_length, :],
past_key_values[idx][2],
past_key_values[idx][3],
)
)
past_key_values = tuple(new_past)
elif "bloom" in model.__class__.__name__.lower():
for idx in range(len(past_key_values)):
new_past.append(
(
past_key_values[idx][0][:, :, :maximum_length],
past_key_values[idx][1][:, :maximum_length, :],
)
)
past_key_values = tuple(new_past)
elif "gptbigcode" in model.__class__.__name__.lower():
if model.config.multi_query:
for idx in range(len(past_key_values)):
past_key_values[idx] = past_key_values[idx][:, :maximum_length, :]
else:
for idx in range(len(past_key_values)):
past_key_values[idx] = past_key_values[idx][:, :, :maximum_length, :]
else:
for idx in range(len(past_key_values)):
new_past.append(
(
past_key_values[idx][0][:, :, :maximum_length, :],
past_key_values[idx][1][:, :, :maximum_length, :],
)
)
past_key_values = tuple(new_past)
return past_key_values
def _split_model_outputs(outputs, new_outputs, cur_len, added_len, is_decoder_attention=False):
"""
Given the (decoder/cross attentions)/(decoder hidden states) for multiple generated tokens, splits it into a tuple
where each member corresponds to a single generated token.
"""
if len(outputs) == 0:
new_tuple = ()
for layer in new_outputs:
last_dim_size = cur_len if is_decoder_attention else layer.shape[-1]
new_tuple += (layer[..., :cur_len, :last_dim_size],)
outputs += (new_tuple,)
cur_len += 1
added_len -= cur_len
for i in range(added_len):
new_tuple = ()
for layer in new_outputs:
last_dim_size = cur_len + i if is_decoder_attention else layer.shape[-1]
new_tuple += (layer[..., i : i + 1, :last_dim_size],)
outputs += (new_tuple,)
return outputs
def top_k_top_p_filtering(
logits: torch.FloatTensor,
top_k: int = 0,
top_p: float = 1.0,
filter_value: float = -float("Inf"),
min_tokens_to_keep: int = 1,
) -> torch.FloatTensor:
"""
Filter a distribution of logits using top-k and/or nucleus (top-p) filtering
Args:
logits: logits distribution shape (batch size, vocabulary size)
top_k (`int`, *optional*, defaults to 0):
If > 0, only keep the top k tokens with highest probability (top-k filtering)
top_p (`float`, *optional*, defaults to 1.0):
If < 1.0, only keep the top tokens with cumulative probability >= top_p (nucleus filtering). Nucleus
filtering is described in Holtzman et al. (http://arxiv.org/abs/1904.09751)
min_tokens_to_keep (`int`, *optional*, defaults to 1):
Minimumber of tokens we keep per batch example in the output.
From: https://gist.github.com/thomwolf/1a5a29f6962089e871b94cbd09daf317
"""
if top_k > 0:
logits = TopKLogitsWarper(top_k=top_k, filter_value=filter_value, min_tokens_to_keep=min_tokens_to_keep)(
None, logits
)
if 0 <= top_p <= 1.0:
logits = TopPLogitsWarper(top_p=top_p, filter_value=filter_value, min_tokens_to_keep=min_tokens_to_keep)(
None, logits
)
return logits
def _ranking_fast(
context_hidden: torch.FloatTensor,
next_hidden: torch.FloatTensor,
next_top_k_probs: torch.FloatTensor,
alpha: float,
beam_width: int,
) -> torch.FloatTensor:
"""
Reranks the top_k candidates based on a degeneration penalty (cosine similarity with previous tokens), as described
in the paper "A Contrastive Framework for Neural Text Generation". Returns the index of the best candidate for each
row in the batch.
"""
norm_context_hidden = context_hidden / context_hidden.norm(dim=2, keepdim=True)
norm_next_hidden = next_hidden / next_hidden.norm(dim=2, keepdim=True)
cosine_matrix = torch.matmul(norm_context_hidden, norm_next_hidden.transpose(1, 2)).squeeze(-1)
degeneration_penalty, _ = torch.max(cosine_matrix, dim=-1)
next_top_k_probs = next_top_k_probs.view(-1)
contrastive_score = (1.0 - alpha) * next_top_k_probs - alpha * degeneration_penalty
contrastive_score = torch.stack(torch.split(contrastive_score, beam_width))
_, selected_idx = contrastive_score.max(dim=-1)
return selected_idx