ArrayComponents

ArrayComponents[array] gives an array in which all identical elements of array are replaced by an integer index representing the component in which the element lies.

ArrayComponents[array,level] finds the identical elements at the specified level in array.

ArrayComponents[array,level,rules] uses a rule or a list of rules for specifying the labels.

Examples

ArrayComponents[{a, b, a, c, b, a}]
(* {1, 2, 1, 3, 2, 1} *)

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