Span

i;;j

represents a span of elements i through j.

i;;

represents a span from i to the end.

;;j

represents a span from the beginning to j.

;;

represents a span that includes all elements.

i;;j;;k

represents a span from i through j in steps of k.

i;;;;k

represents a span from i to the end in steps of k.

;;j;;k

represents a span from the beginning to j in steps of k.

;;;;k

represents a span from the beginning to the end in steps of k.

Details

  • m[[i;;j;;k]] is equivalent to Take[m,{i,j,k}].
  • m[[i;;j]]=v can be used to reset a span of elements in a list or other expression.
  • When used in Part, negative i and j count from the end.
  • In i;;j, i;;j;;k, etc., i and j can be of the form UpTo[n].
  • Any argument of Span[…] can be All, in which case it is interpreted as returning the largest possible number of elements consistent with any possible value of that argument.

Examples

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Basic Examples  (3)

Take a span of elements from a list:

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Out[1]=

Take every third element:

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Assign to a span of elements:

In[1]:=
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Out[1]=
In[2]:=
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Out[2]=
In[3]:=
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Out[3]=

Assign a sequence of different elements:

In[4]:=
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Out[4]=
In[5]:=
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Out[5]=

Scope  (7)

Properties & Relations  (4)

Introduced in 2007
(6.0)
|
Updated in 2017
(11.2)