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# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserve.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from sklearn.metrics import hamming_loss
from sklearn.metrics import accuracy_score as accuracy_metric
from sklearn.metrics import multilabel_confusion_matrix
from sklearn.metrics import precision_recall_fscore_support
from sklearn.metrics import average_precision_score
from sklearn.preprocessing import binarize
import numpy as np
__all__ = [
"multi_hot_encode", "hamming_distance", "accuracy_score",
"precision_recall_fscore", "mean_average_precision"
]
def multi_hot_encode(logits, threshold=0.5):
"""
Encode logits to multi-hot by elementwise for multilabel
"""
return binarize(logits, threshold=threshold)
def hamming_distance(output, target):
"""
Soft metric based label for multilabel classification
Returns:
The smaller the return value is, the better model is.
"""
return hamming_loss(target, output)
def accuracy_score(output, target, base="sample"):
"""
Hard metric for multilabel classification
Args:
output:
target:
base: ["sample", "label"], default="sample"
if "sample", return metric score based sample,
if "label", return metric score based label.
Returns:
accuracy:
"""
assert base in ["sample", "label"], 'must be one of ["sample", "label"]'
if base == "sample":
accuracy = accuracy_metric(target, output)
elif base == "label":
mcm = multilabel_confusion_matrix(target, output)
tns = mcm[:, 0, 0]
fns = mcm[:, 1, 0]
tps = mcm[:, 1, 1]
fps = mcm[:, 0, 1]
accuracy = (sum(tps) + sum(tns)) / (
sum(tps) + sum(tns) + sum(fns) + sum(fps))
return accuracy
def precision_recall_fscore(output, target):
"""
Metric based label for multilabel classification
Returns:
precisions:
recalls:
fscores:
"""
precisions, recalls, fscores, _ = precision_recall_fscore_support(target,
output)
return precisions, recalls, fscores
def mean_average_precision(logits, target):
"""
Calculate average precision
Args:
logits: probability from network before sigmoid or softmax
target: ground truth, 0 or 1
"""
if not (isinstance(logits, np.ndarray) and isinstance(target, np.ndarray)):
raise TypeError("logits and target should be np.ndarray.")
aps = []
for i in range(target.shape[1]):
ap = average_precision_score(target[:, i], logits[:, i])
aps.append(ap)
return np.mean(aps)