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# Label Ranking Average Precision¶

## Module Interface¶

class torchmetrics.classification.MultilabelRankingAveragePrecision(num_labels, ignore_index=None, validate_args=True, **kwargs)[source]

Compute label ranking average precision score for multilabel data [1].

The score is the average over each ground truth label assigned to each sample of the ratio of true vs. total labels with lower score. Best score is 1.

As input to forward and update the metric accepts the following input:

• preds (Tensor): A float tensor of shape (N, C, ...). Preds should be a tensor containing probabilities or logits for each observation. If preds has values outside [0,1] range we consider the input to be logits and will auto apply sigmoid per element.

• target (Tensor): An int tensor of shape (N, C, ...). Target should be a tensor containing ground truth labels, and therefore only contain {0,1} values (except if ignore_index is specified).

Note

Additional dimension ... will be flattened into the batch dimension.

As output to forward and compute the metric returns the following output:

• mlrap (Tensor): A tensor containing the multilabel ranking average precision.

Parameters:
• num_labels (int) – Integer specifying the number of labels

• ignore_index (Optional[int]) – Specifies a target value that is ignored and does not contribute to the metric calculation

• validate_args (bool) – bool indicating if input arguments and tensors should be validated for correctness. Set to False for faster computations.

Example

>>> from torch import rand, randint
>>> from torchmetrics.classification import MultilabelRankingAveragePrecision
>>> preds = rand(10, 5)
>>> target = randint(2, (10, 5))
>>> mlrap = MultilabelRankingAveragePrecision(num_labels=5)
>>> mlrap(preds, target)
tensor(0.7744)
plot(val=None, ax=None)[source]

Plot a single or multiple values from the metric.

Parameters:
• val (Union[Tensor, Sequence[Tensor], None]) – Either a single result from calling metric.forward or metric.compute or a list of these results. If no value is provided, will automatically call metric.compute and plot that result.

• ax (Optional[Axes]) – An matplotlib axis object. If provided will add plot to that axis

Return type:
Returns:

Figure object and Axes object

Raises:

ModuleNotFoundError – If matplotlib is not installed

>>> from torch import rand, randint
>>> # Example plotting a single value
>>> from torchmetrics.classification import MultilabelRankingAveragePrecision
>>> metric = MultilabelRankingAveragePrecision(num_labels=3)
>>> metric.update(rand(20, 3), randint(2, (20, 3)))
>>> fig_, ax_ = metric.plot()
>>> from torch import rand, randint
>>> # Example plotting multiple values
>>> from torchmetrics.classification import MultilabelRankingAveragePrecision
>>> metric = MultilabelRankingAveragePrecision(num_labels=3)
>>> values = [ ]
>>> for _ in range(10):
...     values.append(metric(rand(20, 3), randint(2, (20, 3))))
>>> fig_, ax_ = metric.plot(values)

## Functional Interface¶

torchmetrics.functional.classification.multilabel_ranking_average_precision(preds, target, num_labels, ignore_index=None, validate_args=True)[source]

Compute label ranking average precision score for multilabel data [1].

The score is the average over each ground truth label assigned to each sample of the ratio of true vs. total labels with lower score. Best score is 1.

Accepts the following input tensors:

• preds (float tensor): (N, C, ...). Preds should be a tensor containing probabilities or logits for each observation. If preds has values outside [0,1] range we consider the input to be logits and will auto apply sigmoid per element.

• target (int tensor): (N, C, ...). Target should be a tensor containing ground truth labels, and therefore only contain {0,1} values (except if ignore_index is specified).

Additional dimension ... will be flattened into the batch dimension.

Parameters:
• preds (Tensor) – Tensor with predictions

• target (Tensor) – Tensor with true labels

• num_labels (int) – Integer specifying the number of labels

• ignore_index (Optional[int]) – Specifies a target value that is ignored and does not contribute to the metric calculation

• validate_args (bool) – bool indicating if input arguments and tensors should be validated for correctness. Set to False for faster computations.

Return type:

Tensor

Example

>>> from torch import rand, randint
>>> from torchmetrics.functional.classification import multilabel_ranking_average_precision
>>> preds = rand(10, 5)
>>> target = randint(2, (10, 5))
>>> multilabel_ranking_average_precision(preds, target, num_labels=5)
tensor(0.7744)

References

[1] Tsoumakas, G., Katakis, I., & Vlahavas, I. (2010). Mining multi-label data. In Data mining and knowledge discovery handbook (pp. 667-685). Springer US.