sklearn.metrics.average_precision_score()

sklearn.metrics.average_precision_score(y_true, y_score, average='macro', sample_weight=None) [source]

Compute average precision (AP) from prediction scores

This score corresponds to the area under the precision-recall curve.

Note: this implementation is restricted to the binary classification task or multilabel classification task.

Parameters:	y_true : array, shape = [n_samples] or [n_samples, n_classes] True binary labels in binary label indicators. y_score : array, shape = [n_samples] or [n_samples, n_classes] Target scores, can either be probability estimates of the positive class, confidence values, or non-thresholded measure of decisions (as returned by ?decision_function? on some classifiers). average : string, [None, ?micro?, ?macro? (default), ?samples?, ?weighted?] If `None`, the scores for each class are returned. Otherwise, this determines the type of averaging performed on the data: `'micro':` Calculate metrics globally by considering each element of the label indicator matrix as a label. `'macro':` Calculate metrics for each label, and find their unweighted mean. This does not take label imbalance into account. `'weighted':` Calculate metrics for each label, and find their average, weighted by support (the number of true instances for each label). `'samples':` Calculate metrics for each instance, and find their average. sample_weight : array-like of shape = [n_samples], optional Sample weights.
Returns:	average_precision : float

References

Wikipedia entry for the Average precision

Examples

>>> import numpy as np
>>> from sklearn.metrics import average_precision_score
>>> y_true = np.array([0, 0, 1, 1])
>>> y_scores = np.array([0.1, 0.4, 0.35, 0.8])
>>> average_precision_score(y_true, y_scores)  
0.79...