# Source code for catalyst.utils.metrics.accuracy

```
"""
Various accuracy metrics:
* :func:`accuracy`
* :func:`multi_label_accuracy`
"""
from typing import Optional, Sequence, Union
import numpy as np
import torch
from catalyst.utils.metrics.functional import preprocess_multi_label_metrics
from catalyst.utils.torch import get_activation_fn
[docs]def accuracy(
outputs: torch.Tensor,
targets: torch.Tensor,
topk: Sequence[int] = (1,),
activation: Optional[str] = None,
) -> Sequence[torch.Tensor]:
"""
Computes multi-class accuracy@topk for the specified values of `topk`.
Args:
outputs (torch.Tensor): model outputs, logits
with shape [bs; num_classes]
targets (torch.Tensor): ground truth, labels
with shape [bs; 1]
activation (str): activation to use for model output
topk (Sequence[int]): `topk` for accuracy@topk computing
Returns:
list with computed accuracy@topk
"""
activation_fn = get_activation_fn(activation)
outputs = activation_fn(outputs)
max_k = max(topk)
batch_size = targets.size(0)
if len(outputs.shape) == 1 or outputs.shape[1] == 1:
# binary accuracy
pred = outputs.t()
else:
# multi-class accuracy
_, pred = outputs.topk(max_k, 1, True, True) # noqa: WPS425
pred = pred.t()
correct = pred.eq(targets.long().view(1, -1).expand_as(pred))
output = []
for k in topk:
correct_k = correct[:k].view(-1).float().sum(0, keepdim=True)
output.append(correct_k.mul_(1.0 / batch_size))
return output
[docs]def multi_label_accuracy(
outputs: torch.Tensor,
targets: torch.Tensor,
threshold: Union[float, torch.Tensor],
activation: Optional[str] = None,
) -> torch.Tensor:
"""
Computes multi-label accuracy for the specified activation and threshold.
Args:
outputs (torch.Tensor): NxK tensor that for each of the N examples
indicates the probability of the example belonging to each of
the K classes, according to the model.
targets (torch.Tensor): binary NxK tensort that encodes which of the K
classes are associated with the N-th input
(eg: a row [0, 1, 0, 1] indicates that the example is
associated with classes 2 and 4)
threshold (float): threshold for for model output
activation (str): activation to use for model output
Returns:
computed multi-label accuracy
"""
outputs, targets, _ = preprocess_multi_label_metrics(
outputs=outputs, targets=targets
)
activation_fn = get_activation_fn(activation)
outputs = activation_fn(outputs)
outputs = (outputs > threshold).long()
output = (targets.long() == outputs.long()).sum().float() / np.prod(
targets.shape
)
return output
__all__ = ["accuracy", "multi_label_accuracy"]
```