OrderingBy

OrderingBy[list, f] gives the positions in list at which each successive element of SortBy[list, f] appears.

• OrderingBy[list, f, n] gives the positions in list at which the first n elements of SortBy[list, f] appear.
• OrderingBy[list, f, -n] gives the positions of the last n elements of SortBy[list, f].
• OrderingBy[list, f, n, p] gives positions in list of elements of SortBy[list, f, p].
• OrderingBy[f] represents an operator form of OrderingBy that can be applied to an expression.

Examples

OrderingBy[{"apple", "pear", "banana"}, StringLength]

OrderingBy[{-3, 1, 5, -2}, Abs, 2]

Please visit the official Wolfram Language Reference for more details.