This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.2)

Ordering

Ordering[list]
gives the positions in list at which each successive element of Sort[list] appears.
Ordering[list, n]
gives the positions in list at which the first n elements of Sort[list] appear.
Ordering[list, -n]
gives the positions of the last n elements of Sort[list].
Ordering[list, n, p]
uses Sort[list, p].
  • In a numerical list Ordering[list, n] gives the positions of the n smallest elements. Ordering[list, -n] gives the positions of the n largest elements.
  • If there are several smallest elements in list, Ordering[list, 1] will give only the position of the one that appears first.
  • list[[Ordering[list]]] is the same as Sort[list].
  • Ordering[list, seq] is equivalent to Take[Ordering[list], seq].
  • Ordering[list, All, p] gives the position at which all elements of list appear in Sort[list, p].
  • Ordering can be used on expressions with any head, not only List.
New in 4.1