diff --git a/sklearn/metrics/classification.py b/sklearn/metrics/classification.py index 9eae62a28045e..d1337bdc61aed 100644 --- a/sklearn/metrics/classification.py +++ b/sklearn/metrics/classification.py @@ -1989,16 +1989,18 @@ def hamming_loss(y_true, y_pred, labels=None, sample_weight=None): ----- In multiclass classification, the Hamming loss corresponds to the Hamming distance between ``y_true`` and ``y_pred`` which is equivalent to the - subset ``zero_one_loss`` function. + subset ``zero_one_loss`` function, when `normalize` parameter is set to + True. In multilabel classification, the Hamming loss is different from the subset zero-one loss. The zero-one loss considers the entire set of labels for a given sample incorrect if it does not entirely match the true set of - labels. Hamming loss is more forgiving in that it penalizes the individual - labels. + labels. Hamming loss is more forgiving in that it penalizes only the + individual labels. - The Hamming loss is upperbounded by the subset zero-one loss. When - normalized over samples, the Hamming loss is always between 0 and 1. + The Hamming loss is upperbounded by the subset zero-one loss, when + `normalize` parameter is set to True. It is always between 0 and 1, + lower being better. References ----------