fowlkes_mallows_score (original) (raw)

sklearn.metrics.fowlkes_mallows_score(labels_true, labels_pred, *, sparse='deprecated')[source]#

Measure the similarity of two clusterings of a set of points.

Added in version 0.18.

The Fowlkes-Mallows index (FMI) is defined as the geometric mean of the precision and recall:

FMI = TP / sqrt((TP + FP) * (TP + FN))

Where TP is the number of True Positive (i.e. the number of pairs of points that belong to the same cluster in both labels_true andlabels_pred), FP is the number of False Positive (i.e. the number of pairs of points that belong to the same cluster inlabels_pred but not in labels_true) and FN is the number ofFalse Negative (i.e. the number of pairs of points that belong to the same cluster in labels_true but not in labels_pred).

The score ranges from 0 to 1. A high value indicates a good similarity between two clusters.

Read more in the User Guide.

Parameters:

labels_truearray-like of shape (n_samples,), dtype=int

A clustering of the data into disjoint subsets.

labels_predarray-like of shape (n_samples,), dtype=int

A clustering of the data into disjoint subsets.

sparsebool, default=False

Compute contingency matrix internally with sparse matrix.

Deprecated since version 1.7: The sparse parameter is deprecated and will be removed in 1.9. It has no effect.

Returns:

scorefloat

The resulting Fowlkes-Mallows score.

References

Examples

Perfect labelings are both homogeneous and complete, hence have score 1.0:

from sklearn.metrics.cluster import fowlkes_mallows_score fowlkes_mallows_score([0, 0, 1, 1], [0, 0, 1, 1]) 1.0 fowlkes_mallows_score([0, 0, 1, 1], [1, 1, 0, 0]) 1.0

If classes members are completely split across different clusters, the assignment is totally random, hence the FMI is null:

fowlkes_mallows_score([0, 0, 0, 0], [0, 1, 2, 3]) 0.0