"""The ``metric_stats`` module provides an abstract class for storing
statistics produced over the course of an experiment and summarizing them.
Authors:
* Peter Plantinga 2020
* Mirco Ravanelli 2020
* Gaelle Laperriere 2021
* Sahar Ghannay 2021
"""
import torch
from joblib import Parallel, delayed
from speechbrain.utils.data_utils import undo_padding
from speechbrain.utils.edit_distance import wer_summary, wer_details_for_batch
from speechbrain.dataio.dataio import (
merge_char,
split_word,
extract_concepts_values,
)
from speechbrain.dataio.wer import print_wer_summary, print_alignments
class MetricStats:
"""A default class for storing and summarizing arbitrary metrics.
More complex metrics can be created by sub-classing this class.
Arguments
---------
metric : function
The function to use to compute the relevant metric. Should take
at least two arguments (predictions and targets) and can
optionally take the relative lengths of either or both arguments.
Not usually used in sub-classes.
batch_eval: bool
When True it feeds the evaluation metric with the batched input.
When False and n_jobs=1, it performs metric evaluation one-by-one
in a sequential way. When False and n_jobs>1, the evaluation
runs in parallel over the different inputs using joblib.
n_jobs : int
The number of jobs to use for computing the metric. If this is
more than one, every sample is processed individually, otherwise
the whole batch is passed at once.
Example
-------
>>> from speechbrain.nnet.losses import l1_loss
>>> loss_stats = MetricStats(metric=l1_loss)
>>> loss_stats.append(
... ids=["utterance1", "utterance2"],
... predictions=torch.tensor([[0.1, 0.2], [0.2, 0.3]]),
... targets=torch.tensor([[0.1, 0.2], [0.1, 0.2]]),
... reduction="batch",
... )
>>> stats = loss_stats.summarize()
>>> stats['average']
0.050...
>>> stats['max_score']
0.100...
>>> stats['max_id']
'utterance2'
"""
def __init__(self, metric, n_jobs=1, batch_eval=True):
self.metric = metric
self.n_jobs = n_jobs
self.batch_eval = batch_eval
self.clear()
def clear(self):
"""Creates empty container for storage, removing existing stats."""
self.scores = []
self.ids = []
self.summary = {}
def append(self, ids, *args, **kwargs):
"""Store a particular set of metric scores.
Arguments
---------
ids : list
List of ids corresponding to utterances.
*args, **kwargs
Arguments to pass to the metric function.
"""
self.ids.extend(ids)
if self.batch_eval:
scores = self.metric(*args, **kwargs).detach()
else:
if "predict" not in kwargs or "target" not in kwargs:
raise ValueError(
"Must pass 'predict' and 'target' as kwargs if batch_eval=False"
)
if self.n_jobs == 1:
scores = sequence_evaluation(metric=self.metric, **kwargs)
else:
scores = multiprocess_evaluation(
metric=self.metric, n_jobs=self.n_jobs, **kwargs
)
self.scores.extend(scores)
def summarize(self, field=None):
"""Summarize the metric scores, returning relevant stats.
Arguments
---------
field : str
If provided, only returns selected statistic. If not,
returns all computed statistics.
Returns
-------
float or dict
Returns a float if ``field`` is provided, otherwise
returns a dictionary containing all computed stats.
"""
min_index = torch.argmin(torch.tensor(self.scores))
max_index = torch.argmax(torch.tensor(self.scores))
self.summary = {
"average": float(sum(self.scores) / len(self.scores)),
"min_score": float(self.scores[min_index]),
"min_id": self.ids[min_index],
"max_score": float(self.scores[max_index]),
"max_id": self.ids[max_index],
}
if field is not None:
return self.summary[field]
else:
return self.summary
def write_stats(self, filestream, verbose=False):
"""Write all relevant statistics to file.
Arguments
---------
filestream : file-like object
A stream for the stats to be written to.
verbose : bool
Whether to also print the stats to stdout.
"""
if not self.summary:
self.summarize()
message = f"Average score: {self.summary['average']}\n"
message += f"Min error: {self.summary['min_score']} "
message += f"id: {self.summary['min_id']}\n"
message += f"Max error: {self.summary['max_score']} "
message += f"id: {self.summary['max_id']}\n"
filestream.write(message)
if verbose:
print(message)
def multiprocess_evaluation(metric, predict, target, lengths=None, n_jobs=8):
"""Runs metric evaluation if parallel over multiple jobs."""
if lengths is not None:
lengths = (lengths * predict.size(1)).round().int().cpu()
predict = [p[:length].cpu() for p, length in zip(predict, lengths)]
target = [t[:length].cpu() for t, length in zip(target, lengths)]
while True:
try:
scores = Parallel(n_jobs=n_jobs, timeout=30)(
delayed(metric)(p, t) for p, t in zip(predict, target)
)
break
except Exception as e:
print(e)
print("Evaluation timeout...... (will try again)")
return scores
def sequence_evaluation(metric, predict, target, lengths=None):
"""Runs metric evaluation sequentially over the inputs."""
if lengths is not None:
lengths = (lengths * predict.size(1)).round().int().cpu()
predict = [p[:length].cpu() for p, length in zip(predict, lengths)]
target = [t[:length].cpu() for t, length in zip(target, lengths)]
scores = []
for p, t in zip(predict, target):
score = metric(p, t)
scores.append(score)
return scores
class ErrorRateStats(MetricStats):
"""A class for tracking error rates (e.g., WER, PER).
Arguments
---------
merge_tokens : bool
Whether to merge the successive tokens (used for e.g.,
creating words out of character tokens).
See ``speechbrain.dataio.dataio.merge_char``.
split_tokens : bool
Whether to split tokens (used for e.g. creating
characters out of word tokens).
See ``speechbrain.dataio.dataio.split_word``.
space_token : str
The character to use for boundaries. Used with ``merge_tokens``
this represents character to split on after merge.
Used with ``split_tokens`` the sequence is joined with
this token in between, and then the whole sequence is split.
keep_values : bool
Whether to keep the values of the concepts or not.
extract_concepts_values : bool
Process the predict and target to keep only concepts and values.
tag_in : str
Start of the concept ('<' for exemple).
tag_out : str
End of the concept ('>' for exemple).
Example
-------
>>> cer_stats = ErrorRateStats()
>>> i2l = {0: 'a', 1: 'b'}
>>> cer_stats.append(
... ids=['utterance1'],
... predict=torch.tensor([[0, 1, 1]]),
... target=torch.tensor([[0, 1, 0]]),
... target_len=torch.ones(1),
... ind2lab=lambda batch: [[i2l[int(x)] for x in seq] for seq in batch],
... )
>>> stats = cer_stats.summarize()
>>> stats['WER']
33.33...
>>> stats['insertions']
0
>>> stats['deletions']
0
>>> stats['substitutions']
1
"""
def __init__(
self,
merge_tokens=False,
split_tokens=False,
space_token="_",
keep_values=True,
extract_concepts_values=False,
tag_in="",
tag_out="",
):
self.clear()
self.merge_tokens = merge_tokens
self.split_tokens = split_tokens
self.space_token = space_token
self.extract_concepts_values = extract_concepts_values
self.keep_values = keep_values
self.tag_in = tag_in
self.tag_out = tag_out
def append(
self,
ids,
predict,
target,
predict_len=None,
target_len=None,
ind2lab=None,
):
"""Add stats to the relevant containers.
* See MetricStats.append()
Arguments
---------
ids : list
List of ids corresponding to utterances.
predict : torch.tensor
A predicted output, for comparison with the target output
target : torch.tensor
The correct reference output, for comparison with the prediction.
predict_len : torch.tensor
The predictions relative lengths, used to undo padding if
there is padding present in the predictions.
target_len : torch.tensor
The target outputs' relative lengths, used to undo padding if
there is padding present in the target.
ind2lab : callable
Callable that maps from indices to labels, operating on batches,
for writing alignments.
"""
self.ids.extend(ids)
if predict_len is not None:
predict = undo_padding(predict, predict_len)
if target_len is not None:
target = undo_padding(target, target_len)
if ind2lab is not None:
predict = ind2lab(predict)
target = ind2lab(target)
if self.merge_tokens:
predict = merge_char(predict, space=self.space_token)
target = merge_char(target, space=self.space_token)
if self.split_tokens:
predict = split_word(predict, space=self.space_token)
target = split_word(target, space=self.space_token)
if self.extract_concepts_values:
predict = extract_concepts_values(
predict,
self.keep_values,
self.tag_in,
self.tag_out,
space=self.space_token,
)
target = extract_concepts_values(
target,
self.keep_values,
self.tag_in,
self.tag_out,
space=self.space_token,
)
scores = wer_details_for_batch(ids, target, predict, True)
self.scores.extend(scores)
def summarize(self, field=None):
"""Summarize the error_rate and return relevant statistics.
* See MetricStats.summarize()
"""
self.summary = wer_summary(self.scores)
self.summary["error_rate"] = self.summary["WER"]
if field is not None:
return self.summary[field]
else:
return self.summary
def write_stats(self, filestream):
"""Write all relevant info (e.g., error rate alignments) to file.
* See MetricStats.write_stats()
"""
if not self.summary:
self.summarize()
print_wer_summary(self.summary, filestream)
print_alignments(self.scores, filestream)
class BinaryMetricStats(MetricStats):
"""Tracks binary metrics, such as precision, recall, F1, EER, etc.
"""
def __init__(self, positive_label=1):
self.clear()
self.positive_label = positive_label
def clear(self):
"""Clears the stored metrics."""
self.ids = []
self.scores = []
self.labels = []
self.summary = {}
def append(self, ids, scores, labels):
"""Appends scores and labels to internal lists.
Does not compute metrics until time of summary, since
automatic thresholds (e.g., EER) need full set of scores.
Arguments
---------
ids : list
The string ids for the samples
"""
self.ids.extend(ids)
self.scores.extend(scores.detach())
self.labels.extend(labels.detach())
def summarize(
self, field=None, threshold=None, max_samples=None, beta=1, eps=1e-8
):
"""Compute statistics using a full set of scores.
Full set of fields:
- TP - True Positive
- TN - True Negative
- FP - False Positive
- FN - False Negative
- FAR - False Acceptance Rate
- FRR - False Rejection Rate
- DER - Detection Error Rate (EER if no threshold passed)
- threshold - threshold (EER threshold if no threshold passed)
- precision - Precision (positive predictive value)
- recall - Recall (sensitivity)
- F-score - Balance of precision and recall (equal if beta=1)
- MCC - Matthews Correlation Coefficient
Arguments
---------
field : str
A key for selecting a single statistic. If not provided,
a dict with all statistics is returned.
threshold : float
If no threshold is provided, equal error rate is used.
max_samples: float
How many samples to keep for postive/negative scores.
If no max_samples is provided, all scores are kept.
Only effective when threshold is None.
beta : float
How much to weight precision vs recall in F-score. Default
of 1. is equal weight, while higher values weight recall
higher, and lower values weight precision higher.
eps : float
A small value to avoid dividing by zero.
"""
if isinstance(self.scores, list):
self.scores = torch.stack(self.scores)
self.labels = torch.stack(self.labels)
if threshold is None:
positive_scores = self.scores[
(self.labels == self.positive_label).nonzero(as_tuple=True)
]
negative_scores = self.scores[
(self.labels != self.positive_label).nonzero(as_tuple=True)
]
if max_samples is not None:
if len(positive_scores) > max_samples:
positive_scores, _ = torch.sort(positive_scores)
positive_scores = positive_scores[
[
i
for i in range(
0,
len(positive_scores),
int(len(positive_scores) / max_samples),
)
]
]
if len(negative_scores) > max_samples:
negative_scores, _ = torch.sort(negative_scores)
negative_scores = negative_scores[
[
i
for i in range(
0,
len(negative_scores),
int(len(negative_scores) / max_samples),
)
]
]
eer, threshold = EER(positive_scores, negative_scores)
pred = (self.scores > threshold).float()
true = self.labels
TP = self.summary["TP"] = float(pred.mul(true).sum())
TN = self.summary["TN"] = float((1.0 - pred).mul(1.0 - true).sum())
FP = self.summary["FP"] = float(pred.mul(1.0 - true).sum())
FN = self.summary["FN"] = float((1.0 - pred).mul(true).sum())
self.summary["FAR"] = FP / (FP + TN + eps)
self.summary["FRR"] = FN / (TP + FN + eps)
self.summary["DER"] = (FP + FN) / (TP + TN + eps)
self.summary["threshold"] = threshold
self.summary["precision"] = TP / (TP + FP + eps)
self.summary["recall"] = TP / (TP + FN + eps)
self.summary["F-score"] = (
(1.0 + beta ** 2.0)
* TP
/ ((1.0 + beta ** 2.0) * TP + beta ** 2.0 * FN + FP)
)
self.summary["MCC"] = (TP * TN - FP * FN) / (
(TP + FP) * (TP + FN) * (TN + FP) * (TN + FN) + eps
) ** 0.5
if field is not None:
return self.summary[field]
else:
return self.summary
def EER(positive_scores, negative_scores):
"""Computes the EER (and its threshold).
Arguments
---------
positive_scores : torch.tensor
The scores from entries of the same class.
negative_scores : torch.tensor
The scores from entries of different classes.
Example
-------
>>> positive_scores = torch.tensor([0.6, 0.7, 0.8, 0.5])
>>> negative_scores = torch.tensor([0.4, 0.3, 0.2, 0.1])
>>> val_eer, threshold = EER(positive_scores, negative_scores)
>>> val_eer
0.0
"""
thresholds, _ = torch.sort(torch.cat([positive_scores, negative_scores]))
thresholds = torch.unique(thresholds)
interm_thresholds = (thresholds[0:-1] + thresholds[1:]) / 2
thresholds, _ = torch.sort(torch.cat([thresholds, interm_thresholds]))
min_index = 0
final_FRR = 0
final_FAR = 0
for i, cur_thresh in enumerate(thresholds):
pos_scores_threshold = positive_scores <= cur_thresh
FRR = (pos_scores_threshold.sum(0)).float() / positive_scores.shape[0]
del pos_scores_threshold
neg_scores_threshold = negative_scores > cur_thresh
FAR = (neg_scores_threshold.sum(0)).float() / negative_scores.shape[0]
del neg_scores_threshold
if (FAR - FRR).abs().item() < abs(final_FAR - final_FRR) or i == 0:
min_index = i
final_FRR = FRR.item()
final_FAR = FAR.item()
EER = (final_FAR + final_FRR) / 2
return float(EER), float(thresholds[min_index])
def minDCF(
positive_scores, negative_scores, c_miss=1.0, c_fa=1.0, p_target=0.01
):
"""Computes the minDCF metric normally used to evaluate speaker verification
systems. The min_DCF is the minimum of the following C_det function computed
within the defined threshold range:
C_det = c_miss * p_miss * p_target + c_fa * p_fa * (1 -p_target)
where p_miss is the missing probability and p_fa is the probability of having
a false alarm.
Arguments
---------
positive_scores : torch.tensor
The scores from entries of the same class.
negative_scores : torch.tensor
The scores from entries of different classes.
c_miss : float
Cost assigned to a missing error (default 1.0).
c_fa : float
Cost assigned to a false alarm (default 1.0).
p_target: float
Prior probability of having a target (default 0.01).
Example
-------
>>> positive_scores = torch.tensor([0.6, 0.7, 0.8, 0.5])
>>> negative_scores = torch.tensor([0.4, 0.3, 0.2, 0.1])
>>> val_minDCF, threshold = minDCF(positive_scores, negative_scores)
>>> val_minDCF
0.0
"""
thresholds, _ = torch.sort(torch.cat([positive_scores, negative_scores]))
thresholds = torch.unique(thresholds)
interm_thresholds = (thresholds[0:-1] + thresholds[1:]) / 2
thresholds, _ = torch.sort(torch.cat([thresholds, interm_thresholds]))
positive_scores = torch.cat(
len(thresholds) * [positive_scores.unsqueeze(0)]
)
pos_scores_threshold = positive_scores.transpose(0, 1) <= thresholds
p_miss = (pos_scores_threshold.sum(0)).float() / positive_scores.shape[1]
del positive_scores
del pos_scores_threshold
negative_scores = torch.cat(
len(thresholds) * [negative_scores.unsqueeze(0)]
)
neg_scores_threshold = negative_scores.transpose(0, 1) > thresholds
p_fa = (neg_scores_threshold.sum(0)).float() / negative_scores.shape[1]
del negative_scores
del neg_scores_threshold
c_det = c_miss * p_miss * p_target + c_fa * p_fa * (1 - p_target)
c_min, min_index = torch.min(c_det, dim=0)
return float(c_min), float(thresholds[min_index])
class ClassificationStats(MetricStats):
"""Computes statistics pertaining to multi-label
classification tasks, as well as tasks that can be loosely interpreted as such for the purpose of
evaluations
Example
-------
>>> import sys
>>> from speechbrain.utils.metric_stats import ClassificationStats
>>> cs = ClassificationStats()
>>> cs.append(
... ids=["ITEM1", "ITEM2", "ITEM3", "ITEM4"],
... predictions=[
... "M EY K AH",
... "T EY K",
... "B AE D",
... "M EY K",
... ],
... targets=[
... "M EY K",
... "T EY K",
... "B AE D",
... "M EY K",
... ],
... categories=[
... "make",
... "take",
... "bad",
... "make"
... ]
... )
>>> cs.write_stats(sys.stdout)
Overall Accuracy: 75%
<BLANKLINE>
Class-Wise Accuracy
-------------------
bad -> B AE D : 1 / 1 (100.00%)
make -> M EY K: 1 / 2 (50.00%)
take -> T EY K: 1 / 1 (100.00%)
<BLANKLINE>
Confusion
---------
Target: bad -> B AE D
-> B AE D : 1 / 1 (100.00%)
Target: make -> M EY K
-> M EY K : 1 / 2 (50.00%)
-> M EY K AH: 1 / 2 (50.00%)
Target: take -> T EY K
-> T EY K : 1 / 1 (100.00%)
>>> summary = cs.summarize()
>>> summary['accuracy']
0.75
>>> summary['classwise_stats'][('bad', 'B AE D')]
{'total': 1.0, 'correct': 1.0, 'accuracy': 1.0}
>>> summary['classwise_stats'][('make', 'M EY K')]
{'total': 2.0, 'correct': 1.0, 'accuracy': 0.5}
>>> summary['keys']
[('bad', 'B AE D'), ('make', 'M EY K'), ('take', 'T EY K')]
>>> summary['predictions']
['B AE D', 'M EY K', 'M EY K AH', 'T EY K']
>>> summary['classwise_total']
{('bad', 'B AE D'): 1.0, ('make', 'M EY K'): 2.0, ('take', 'T EY K'): 1.0}
>>> summary['classwise_correct']
{('bad', 'B AE D'): 1.0, ('make', 'M EY K'): 1.0, ('take', 'T EY K'): 1.0}
>>> summary['classwise_accuracy']
{('bad', 'B AE D'): 1.0, ('make', 'M EY K'): 0.5, ('take', 'T EY K'): 1.0}
"""
def __init__(self):
super()
self.clear()
self.summary = None
def append(self, ids, predictions, targets, categories=None):
"""
Appends inputs, predictions and targets to internal
lists
Arguments
---------
ids: list
the string IDs for the samples
predictions: list
the model's predictions (human-interpretable,
preferably strings)
targets: list
the ground truths (human-interpretable, preferably strings)
categories: list
an additional way to classify training
samples. If available, the categories will
be combined with targets
"""
self.ids.extend(ids)
self.predictions.extend(predictions)
self.targets.extend(targets)
if categories is not None:
self.categories.extend(categories)
def summarize(self, field=None):
"""Summarize the classification metric scores
The following statistics are computed:
accuracy: the overall accuracy (# correct / # total)
confusion_matrix: a dictionary of type
{(target, prediction): num_entries} representing
the confusion matrix
classwise_stats: computes the total number of samples,
the number of correct classifications and accuracy
for each class
keys: all available class keys, which can be either target classes
or (category, target) tuples
predictions: all available predictions all predicions the model
has made
Arguments
---------
field : str
If provided, only returns selected statistic. If not,
returns all computed statistics.
Returns
-------
float or dict
Returns a float if ``field`` is provided, otherwise
returns a dictionary containing all computed stats.
"""
self._build_lookups()
confusion_matrix = self._compute_confusion_matrix()
self.summary = {
"accuracy": self._compute_accuracy(),
"confusion_matrix": confusion_matrix,
"classwise_stats": self._compute_classwise_stats(confusion_matrix),
"keys": self._available_keys,
"predictions": self._available_predictions,
}
for stat in ["total", "correct", "accuracy"]:
self.summary[f"classwise_{stat}"] = {
key: key_stats[stat]
for key, key_stats in self.summary["classwise_stats"].items()
}
if field is not None:
return self.summary[field]
else:
return self.summary
def _compute_accuracy(self):
return sum(
prediction == target
for prediction, target in zip(self.predictions, self.targets)
) / len(self.ids)
def _build_lookups(self):
self._available_keys = self._get_keys()
self._available_predictions = list(
sorted(set(prediction for prediction in self.predictions))
)
self._keys_lookup = self._index_lookup(self._available_keys)
self._predictions_lookup = self._index_lookup(
self._available_predictions
)
def _compute_confusion_matrix(self):
confusion_matrix = torch.zeros(
len(self._available_keys), len(self._available_predictions)
)
for key, prediction in self._get_confusion_entries():
key_idx = self._keys_lookup[key]
prediction_idx = self._predictions_lookup[prediction]
confusion_matrix[key_idx, prediction_idx] += 1
return confusion_matrix
def _compute_classwise_stats(self, confusion_matrix):
total = confusion_matrix.sum(dim=-1)
key_targets = (
self._available_keys
if not self.categories
else [target for _, target in self._available_keys]
)
correct = torch.tensor(
[
(
confusion_matrix[idx, self._predictions_lookup[target]]
if target in self._predictions_lookup
else 0
)
for idx, target in enumerate(key_targets)
]
)
accuracy = correct / total
return {
key: {
"total": item_total.item(),
"correct": item_correct.item(),
"accuracy": item_accuracy.item(),
}
for key, item_total, item_correct, item_accuracy in zip(
self._available_keys, total, correct, accuracy
)
}
def _get_keys(self):
if self.categories:
keys = zip(self.categories, self.targets)
else:
keys = self.targets
return list(sorted(set(keys)))
def _get_confusion_entries(self):
if self.categories:
result = (
((category, target), prediction)
for category, target, prediction in zip(
self.categories, self.targets, self.predictions
)
)
else:
result = zip(self.targets, self.predictions)
result = list(result)
return result
def _index_lookup(self, items):
return {item: idx for idx, item in enumerate(items)}
def clear(self):
"""Clears the collected statistics"""
self.ids = []
self.predictions = []
self.targets = []
self.categories = []
def write_stats(self, filestream):
"""Outputs the stats to the specified filestream in a human-readable format
Arguments
---------
filestream: file
a file-like object
"""
if self.summary is None:
self.summarize()
print(
f"Overall Accuracy: {self.summary['accuracy']:.0%}", file=filestream
)
print(file=filestream)
self._write_classwise_stats(filestream)
print(file=filestream)
self._write_confusion(filestream)
def _write_classwise_stats(self, filestream):
self._write_header("Class-Wise Accuracy", filestream=filestream)
key_labels = {
key: self._format_key_label(key) for key in self._available_keys
}
longest_key_label = max(len(label) for label in key_labels.values())
for key in self._available_keys:
stats = self.summary["classwise_stats"][key]
padded_label = self._pad_to_length(
self._format_key_label(key), longest_key_label
)
print(
f"{padded_label}: {int(stats['correct'])} / {int(stats['total'])} ({stats['accuracy']:.2%})",
file=filestream,
)
def _write_confusion(self, filestream):
self._write_header("Confusion", filestream=filestream)
longest_prediction = max(
len(prediction) for prediction in self._available_predictions
)
confusion_matrix = self.summary["confusion_matrix"].int()
totals = confusion_matrix.sum(dim=-1)
for key, key_predictions, total in zip(
self._available_keys, confusion_matrix, totals
):
target_label = self._format_key_label(key)
print(f"Target: {target_label}", file=filestream)
(indexes,) = torch.where(key_predictions > 0)
total = total.item()
for index in indexes:
count = key_predictions[index].item()
prediction = self._available_predictions[index]
padded_label = self._pad_to_length(
prediction, longest_prediction
)
print(
f" -> {padded_label}: {count} / {total} ({count / total:.2%})",
file=filestream,
)
def _write_header(self, header, filestream):
print(header, file=filestream)
print("-" * len(header), file=filestream)
def _pad_to_length(self, label, length):
padding = max(0, length - len(label))
return label + (" " * padding)
def _format_key_label(self, key):
if self.categories:
category, target = key
label = f"{category} -> {target}"
else:
label = key
return label