mars.learn.metrics.multilabel_confusion_matrix#

mars.learn.metrics.multilabel_confusion_matrix(y_true, y_pred, *, sample_weight=None, labels=None, samplewise=False, session=None, run_kwargs=None)[source]#

Compute a confusion matrix for each class or sample.

Compute class-wise (default) or sample-wise (samplewise=True) multilabel confusion matrix to evaluate the accuracy of a classification, and output confusion matrices for each class or sample.

In multilabel confusion matrix \(MCM\), the count of true negatives is \(MCM_{:,0,0}\), false negatives is \(MCM_{:,1,0}\), true positives is \(MCM_{:,1,1}\) and false positives is \(MCM_{:,0,1}\).

Multiclass data will be treated as if binarized under a one-vs-rest transformation. Returned confusion matrices will be in the order of sorted unique labels in the union of (y_true, y_pred).

Read more in the User Guide.

Parameters

  • y_true ({array-like, sparse matrix} of shape (n_samples, n_outputs) or (n_samples,)) – Ground truth (correct) target values.

  • y_pred ({array-like, sparse matrix} of shape (n_samples, n_outputs) or (n_samples,)) – Estimated targets as returned by a classifier.

  • sample_weight (array-like of shape (n_samples,), default=None) – Sample weights.

  • labels (array-like of shape (n_classes,), default=None) – A list of classes or column indices to select some (or to force inclusion of classes absent from the data).

  • samplewise (bool, default=False) – In the multilabel case, this calculates a confusion matrix per sample.

Returns

multi_confusion – A 2x2 confusion matrix corresponding to each output in the input. When calculating class-wise multi_confusion (default), then n_outputs = n_labels; when calculating sample-wise multi_confusion (samplewise=True), n_outputs = n_samples. If labels is defined, the results will be returned in the order specified in labels, otherwise the results will be returned in sorted order by default.

Return type

ndarray of shape (n_outputs, 2, 2)

See also

confusion_matrix

Compute confusion matrix to evaluate the accuracy of a classifier.

Notes

The multilabel_confusion_matrix calculates class-wise or sample-wise multilabel confusion matrices, and in multiclass tasks, labels are binarized under a one-vs-rest way; while confusion_matrix() calculates one confusion matrix for confusion between every two classes.

Examples

Multiclass case:

>>> import mars.tensor as mt
>>> from mars.learn.metrics import multilabel_confusion_matrix
>>> y_true = ["cat", "ant", "cat", "cat", "ant", "bird"]
>>> y_pred = ["ant", "ant", "cat", "cat", "ant", "cat"]
>>> multilabel_confusion_matrix(y_true, y_pred,
...                             labels=["ant", "bird", "cat"])
array([[[3, 1],
        [0, 2]],

       [[5, 0],
        [1, 0]],

       [[2, 1],
        [1, 2]]])

Multilabel-indicator case not implemented yet.