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average_precision.py
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average_precision.py
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# Copyright The 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 Optional
import torch
from torch import Tensor, tensor
from torchmetrics.utilities.checks import _check_retrieval_functional_inputs
def retrieval_average_precision(preds: Tensor, target: Tensor, top_k: Optional[int] = None) -> Tensor:
"""Compute average precision (for information retrieval), as explained in `IR Average precision`_.
``preds`` and ``target`` should be of the same shape and live on the same device. If no ``target`` is ``True``,
``0`` is returned. ``target`` must be either `bool` or `integers` and ``preds`` must be ``float``,
otherwise an error is raised.
Args:
preds: estimated probabilities of each document to be relevant.
target: ground truth about each document being relevant or not.
top_k: consider only the top k elements (default: ``None``, which considers them all)
Return:
a single-value tensor with the average precision (AP) of the predictions ``preds`` w.r.t. the labels ``target``.
Raises:
ValueError:
If ``top_k`` is not ``None`` or an integer larger than 0.
Example:
>>> from torchmetrics.functional.retrieval import retrieval_average_precision
>>> preds = tensor([0.2, 0.3, 0.5])
>>> target = tensor([True, False, True])
>>> retrieval_average_precision(preds, target)
tensor(0.8333)
"""
preds, target = _check_retrieval_functional_inputs(preds, target)
top_k = top_k or preds.shape[-1]
if not isinstance(top_k, int) and top_k <= 0:
raise ValueError(f"Argument ``top_k`` has to be a positive integer or None, but got {top_k}.")
target = target[preds.topk(min(top_k, preds.shape[-1]), sorted=True, dim=-1)[1]]
if not target.sum():
return tensor(0.0, device=preds.device)
positions = torch.arange(1, len(target) + 1, device=target.device, dtype=torch.float32)[target > 0]
return torch.div((torch.arange(len(positions), device=positions.device, dtype=torch.float32) + 1), positions).mean()