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tf_metrics.py
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tf_metrics.py
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"""
Multiclass
from:
https://github.com/guillaumegenthial/tf_metrics/blob/master/tf_metrics/__init__.py
"""
__author__ = "Guillaume Genthial"
import numpy as np
import tensorflow as tf
from tensorflow.python.ops.metrics_impl import _streaming_confusion_matrix
def precision(labels, predictions, num_classes, pos_indices=None,
weights=None, average='micro'):
"""Multi-class precision metric for Tensorflow
Parameters
----------
labels : Tensor of tf.int32 or tf.int64
The true labels
predictions : Tensor of tf.int32 or tf.int64
The predictions, same shape as labels
num_classes : int
The number of classes
pos_indices : list of int, optional
The indices of the positive classes, default is all
weights : Tensor of tf.int32, optional
Mask, must be of compatible shape with labels
average : str, optional
'micro': counts the total number of true positives, false
positives, and false negatives for the classes in
`pos_indices` and infer the metric from it.
'macro': will compute the metric separately for each class in
`pos_indices` and average. Will not account for class
imbalance.
'weighted': will compute the metric separately for each class in
`pos_indices` and perform a weighted average by the total
number of true labels for each class.
Returns
-------
tuple of (scalar float Tensor, update_op)
"""
cm, op = _streaming_confusion_matrix(
labels, predictions, num_classes, weights)
pr, _, _ = metrics_from_confusion_matrix(
cm, pos_indices, average=average)
op, _, _ = metrics_from_confusion_matrix(
op, pos_indices, average=average)
return (pr, op)
def recall(labels, predictions, num_classes, pos_indices=None, weights=None,
average='micro'):
"""Multi-class recall metric for Tensorflow
Parameters
----------
labels : Tensor of tf.int32 or tf.int64
The true labels
predictions : Tensor of tf.int32 or tf.int64
The predictions, same shape as labels
num_classes : int
The number of classes
pos_indices : list of int, optional
The indices of the positive classes, default is all
weights : Tensor of tf.int32, optional
Mask, must be of compatible shape with labels
average : str, optional
'micro': counts the total number of true positives, false
positives, and false negatives for the classes in
`pos_indices` and infer the metric from it.
'macro': will compute the metric separately for each class in
`pos_indices` and average. Will not account for class
imbalance.
'weighted': will compute the metric separately for each class in
`pos_indices` and perform a weighted average by the total
number of true labels for each class.
Returns
-------
tuple of (scalar float Tensor, update_op)
"""
cm, op = _streaming_confusion_matrix(
labels, predictions, num_classes, weights)
_, re, _ = metrics_from_confusion_matrix(
cm, pos_indices, average=average)
_, op, _ = metrics_from_confusion_matrix(
op, pos_indices, average=average)
return (re, op)
def f1(labels, predictions, num_classes, pos_indices=None, weights=None,
average='micro'):
return fbeta(labels, predictions, num_classes, pos_indices, weights,
average)
def fbeta(labels, predictions, num_classes, pos_indices=None, weights=None,
average='micro', beta=1):
"""Multi-class fbeta metric for Tensorflow
Parameters
----------
labels : Tensor of tf.int32 or tf.int64
The true labels
predictions : Tensor of tf.int32 or tf.int64
The predictions, same shape as labels
num_classes : int
The number of classes
pos_indices : list of int, optional
The indices of the positive classes, default is all
weights : Tensor of tf.int32, optional
Mask, must be of compatible shape with labels
average : str, optional
'micro': counts the total number of true positives, false
positives, and false negatives for the classes in
`pos_indices` and infer the metric from it.
'macro': will compute the metric separately for each class in
`pos_indices` and average. Will not account for class
imbalance.
'weighted': will compute the metric separately for each class in
`pos_indices` and perform a weighted average by the total
number of true labels for each class.
beta : int, optional
Weight of precision in harmonic mean
Returns
-------
tuple of (scalar float Tensor, update_op)
"""
cm, op = _streaming_confusion_matrix(
labels, predictions, num_classes, weights)
_, _, fbeta = metrics_from_confusion_matrix(
cm, pos_indices, average=average, beta=beta)
_, _, op = metrics_from_confusion_matrix(
op, pos_indices, average=average, beta=beta)
return (fbeta, op)
def safe_div(numerator, denominator):
"""Safe division, return 0 if denominator is 0"""
numerator, denominator = tf.to_float(numerator), tf.to_float(denominator)
zeros = tf.zeros_like(numerator, dtype=numerator.dtype)
denominator_is_zero = tf.equal(denominator, zeros)
return tf.where(denominator_is_zero, zeros, numerator / denominator)
def pr_re_fbeta(cm, pos_indices, beta=1):
"""Uses a confusion matrix to compute precision, recall and fbeta"""
num_classes = cm.shape[0]
neg_indices = [i for i in range(num_classes) if i not in pos_indices]
cm_mask = np.ones([num_classes, num_classes])
cm_mask[neg_indices, neg_indices] = 0
diag_sum = tf.reduce_sum(tf.diag_part(cm * cm_mask))
cm_mask = np.ones([num_classes, num_classes])
cm_mask[:, neg_indices] = 0
tot_pred = tf.reduce_sum(cm * cm_mask)
cm_mask = np.ones([num_classes, num_classes])
cm_mask[neg_indices, :] = 0
tot_gold = tf.reduce_sum(cm * cm_mask)
pr = safe_div(diag_sum, tot_pred)
re = safe_div(diag_sum, tot_gold)
fbeta = safe_div((1. + beta**2) * pr * re, beta**2 * pr + re)
return pr, re, fbeta
def metrics_from_confusion_matrix(cm, pos_indices=None, average='micro',
beta=1):
"""Precision, Recall and F1 from the confusion matrix
Parameters
----------
cm : tf.Tensor of type tf.int32, of shape (num_classes, num_classes)
The streaming confusion matrix.
pos_indices : list of int, optional
The indices of the positive classes
beta : int, optional
Weight of precision in harmonic mean
average : str, optional
'micro', 'macro' or 'weighted'
"""
num_classes = cm.shape[0]
if pos_indices is None:
pos_indices = [i for i in range(num_classes)]
if average == 'micro':
return pr_re_fbeta(cm, pos_indices, beta)
elif average in {'macro', 'weighted'}:
precisions, recalls, fbetas, n_golds = [], [], [], []
for idx in pos_indices:
pr, re, fbeta = pr_re_fbeta(cm, [idx], beta)
precisions.append(pr)
recalls.append(re)
fbetas.append(fbeta)
cm_mask = np.zeros([num_classes, num_classes])
cm_mask[idx, :] = 1
n_golds.append(tf.to_float(tf.reduce_sum(cm * cm_mask)))
if average == 'macro':
pr = tf.reduce_mean(precisions)
re = tf.reduce_mean(recalls)
fbeta = tf.reduce_mean(fbetas)
return pr, re, fbeta
if average == 'weighted':
n_gold = tf.reduce_sum(n_golds)
pr_sum = sum(p * n for p, n in zip(precisions, n_golds))
pr = safe_div(pr_sum, n_gold)
re_sum = sum(r * n for r, n in zip(recalls, n_golds))
re = safe_div(re_sum, n_gold)
fbeta_sum = sum(f * n for f, n in zip(fbetas, n_golds))
fbeta = safe_div(fbeta_sum, n_gold)
return pr, re, fbeta
else:
raise NotImplementedError()