multilabel_confusion_matrix (original) (raw)

sklearn.metrics.multilabel_confusion_matrix(y_true, y_pred, *, sample_weight=None, labels=None, samplewise=False)[source]#

Compute a confusion matrix for each class or sample.

Added in version 0.21.

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_weightarray-like of shape (n_samples,), default=None

Sample weights.

labelsarray-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).

samplewisebool, default=False

In the multilabel case, this calculates a confusion matrix per sample.

Returns:

multi_confusionndarray of shape (n_outputs, 2, 2)

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.

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; whileconfusion_matrix calculates one confusion matrix for confusion between every two classes.

Examples

Multilabel-indicator case:

import numpy as np from sklearn.metrics import multilabel_confusion_matrix y_true = np.array([[1, 0, 1], ... [0, 1, 0]]) y_pred = np.array([[1, 0, 0], ... [0, 1, 1]]) multilabel_confusion_matrix(y_true, y_pred) array([[[1, 0], [0, 1]],

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

   [[0, 1],
    [1, 0]]])

Multiclass case:

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]]])