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Riffle[{e1,e2,…},x]

gives {e1,x,e2,x,…}.

Riffle[{e1,e2,…},{x1,x2,…}]

gives {e1,x1,e2,x2,…}.

Riffle[list,x,n]

yields a list in which every n^(th) element is x.

Riffle[list,x,{imin,imax,n}]

yields a list in which x appears if possible at positions imin, imin+n, imin+2n, … , imax.

Details
Details and Options Details and Options
Examples  
Basic Examples  
Scope  
Applications  
Properties & Relations  
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Riffle

Riffle[{e1,e2,…},x]

gives {e1,x,e2,x,…}.

Riffle[{e1,e2,…},{x1,x2,…}]

gives {e1,x1,e2,x2,…}.

Riffle[list,x,n]

yields a list in which every n^(th) element is x.

Riffle[list,x,{imin,imax,n}]

yields a list in which x appears if possible at positions imin, imin+n, imin+2n, … , imax.

Details

  • If there are fewer xi than gaps between ei in Riffle[{e1,e2,…},{x1,x2,…}], the xi are used cyclically.
  • Riffle[{e},x] gives {e}.
  • The specification {imin,imax,n} is of the type used in Take. Negative indices count from the end of the list.
  • Riffle[list,x] is equivalent to Riffle[list,x,{2,-2,2}].
  • Riffle[list,x,n] is equivalent to Riffle[list,x,{n,-2,n}].
  • In Riffle[list,xlist], if list and xlist are of the same length, then their elements are directly interleaved, so that the last element of the result is the last element of xlist.
  • Riffle works with SparseArray objects.

Examples

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Basic Examples  (3)

Riffle x between successive elements in a list:

Riffle in x and y cyclically:

Riffle in x at every 3^(rd) position:

Scope  (7)

Riffle in x at every other position:

Include x at the beginning and end:

Use step 3:

Start riffling in x only at position 5:

Cyclically riffle in x and y:

Intersperse two lists:

Riffle works on SparseArray objects:

Applications  (5)

Insert spaces between words:

Create a directory name from a path list:

Insert 0s between successive integers:

Alternate positive and negative integers:

Insert commas at every 4^(th) character:

Properties & Relations  (1)

Riffle is related to Transpose:

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

Text

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

CMS

Wolfram Language. 2007. "Riffle." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/Riffle.html.

APA

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

BibTeX

@misc{reference.wolfram_2025_riffle, author="Wolfram Research", title="{Riffle}", year="2007", howpublished="\url{https://reference.wolfram.com/language/ref/Riffle.html}", note=[Accessed: 15-August-2025]}

BibLaTeX

@online{reference.wolfram_2025_riffle, organization={Wolfram Research}, title={Riffle}, year={2007}, url={https://reference.wolfram.com/language/ref/Riffle.html}, note=[Accessed: 15-August-2025]}