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 (3)Basic Examples (3)

Find the ordering that sorts a list:

In[1]:=
Click for copyable input
Out[1]=

Apply the ordering:

In[2]:=
Click for copyable input
Out[2]=

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

In[1]:=
Click for copyable input
Out[1]=

Find the position of the largest element:

In[1]:=
Click for copyable input
Out[1]=
New in 4.1
New to Mathematica? Find your learning path »
Have a question? Ask support »