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].

DetailsDetails

  • 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.
  • 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.

ExamplesExamplesopen allclose all

Basic Examples  (4)Basic Examples  (4)

Find the ordering that sorts a list:

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Apply the ordering:

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Find the positions of the 4 smallest elements in a list:

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Find the position of the largest element:

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Find the ordering of values in an Association:

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Introduced in 2000
(4.1)