ClusteringComponents

ClusteringComponents[array] gives an array where each element is replaced by an integer index representing its cluster.

ClusteringComponents[array, n] finds n clusters.

ClusteringComponents[image] finds clusters of pixels with similar values in image.

Examples

Cluster a list of values:

ClusteringComponents[{1, 1.1, 5, 5.1, 10}]
(* {1, 1, 2, 2, 3} *)

Find 2 clusters:

ClusteringComponents[{1, 2, 10, 11, 12}, 2]
(* {1, 1, 2, 2, 2} *)

Please visit the official Wolfram Language Reference for more details.