# 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

open allclose all

## Basic Examples(3)

Take a span of elements from a list:

Take every third element:

Assign to a span of elements:

Assign a sequence of different elements:

## Scope(7)

Negative indices count from the end:

A negative step size extracts elements in reverse order:

Take all elements from the third position to the end:

Take the first five characters:

Take every other element:

Use UpTo to restrict the right endpoint of the span to the length of the list:

Use UpTo to restrict the left endpoint of the span to the length of the list:

## Properties & Relations(4)

All in the first argument of Span is equivalent to the value 1:

All in the second argument of Span is equivalent to the value -1:

All in the third argument of Span is equivalent to the value 1 or -1:

The value is chosen to given a non-empty range:

When operating on the expression expr, UpTo[n] is equivalent to Min[n,Length[expr]]:

Verify the equivalence:

In this case, only the element b is extracted:

Wolfram Research (2007), Span, Wolfram Language function, https://reference.wolfram.com/language/ref/Span.html (updated 2017).

#### Text

Wolfram Research (2007), Span, Wolfram Language function, https://reference.wolfram.com/language/ref/Span.html (updated 2017).

#### BibTeX

@misc{reference.wolfram_2021_span, author="Wolfram Research", title="{Span}", year="2017", howpublished="\url{https://reference.wolfram.com/language/ref/Span.html}", note=[Accessed: 17-June-2021 ]}

#### BibLaTeX

@online{reference.wolfram_2021_span, organization={Wolfram Research}, title={Span}, year={2017}, url={https://reference.wolfram.com/language/ref/Span.html}, note=[Accessed: 17-June-2021 ]}

#### CMS

Wolfram Language. 2007. "Span." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2017. https://reference.wolfram.com/language/ref/Span.html.

#### APA

Wolfram Language. (2007). Span. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Span.html