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average_precision.py
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average_precision.py
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# Copyright The PyTorch Lightning team.
#
# 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 typing import List, Optional, Sequence, Tuple, Union
import torch
from torchmetrics.functional.classification.precision_recall_curve import (
_precision_recall_curve_compute,
_precision_recall_curve_update,
)
def _average_precision_update(
preds: torch.Tensor,
target: torch.Tensor,
num_classes: Optional[int] = None,
pos_label: Optional[int] = None,
) -> Tuple[torch.Tensor, torch.Tensor, int, int]:
return _precision_recall_curve_update(preds, target, num_classes, pos_label)
def _average_precision_compute(
preds: torch.Tensor,
target: torch.Tensor,
num_classes: int,
pos_label: int,
sample_weights: Optional[Sequence] = None
) -> Union[List[torch.Tensor], torch.Tensor]:
precision, recall, _ = _precision_recall_curve_compute(preds, target, num_classes, pos_label)
# Return the step function integral
# The following works because the last entry of precision is
# guaranteed to be 1, as returned by precision_recall_curve
if num_classes == 1:
return -torch.sum((recall[1:] - recall[:-1]) * precision[:-1])
res = []
for p, r in zip(precision, recall):
res.append(-torch.sum((r[1:] - r[:-1]) * p[:-1]))
return res
def average_precision(
preds: torch.Tensor,
target: torch.Tensor,
num_classes: Optional[int] = None,
pos_label: Optional[int] = None,
sample_weights: Optional[Sequence] = None,
) -> Union[List[torch.Tensor], torch.Tensor]:
"""
Computes the average precision score.
Args:
preds: predictions from model (logits or probabilities)
target: ground truth values
num_classes: integer with number of classes. Not nessesary to provide
for binary problems.
pos_label: integer determining the positive class. Default is ``None``
which for binary problem is translate to 1. For multiclass problems
this argument should not be set as we iteratively change it in the
range [0,num_classes-1]
sample_weights: sample weights for each data point
Returns:
tensor with average precision. If multiclass will return list
of such tensors, one for each class
Example (binary case):
>>> pred = torch.tensor([0, 1, 2, 3])
>>> target = torch.tensor([0, 1, 1, 1])
>>> average_precision(pred, target, pos_label=1)
tensor(1.)
Example (multiclass case):
>>> pred = torch.tensor([[0.75, 0.05, 0.05, 0.05, 0.05],
... [0.05, 0.75, 0.05, 0.05, 0.05],
... [0.05, 0.05, 0.75, 0.05, 0.05],
... [0.05, 0.05, 0.05, 0.75, 0.05]])
>>> target = torch.tensor([0, 1, 3, 2])
>>> average_precision(pred, target, num_classes=5)
[tensor(1.), tensor(1.), tensor(0.2500), tensor(0.2500), tensor(nan)]
"""
preds, target, num_classes, pos_label = _average_precision_update(preds, target, num_classes, pos_label)
return _average_precision_compute(preds, target, num_classes, pos_label, sample_weights)