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Built-in Mathematica Symbol

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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

element is x.

Riffle[list, x, {i_min, i_max, n}]
yields a list in which x appears if possible at positions i_min, i_min+n, i_min+2n, ... , i_max.

MORE INFORMATION

If there are fewer x_i than gaps between e_i in Riffle[{e₁, e₂, ...}, {x₁, x₂, ...}], the x_i are used cyclically.

Riffle[{e}, x] gives {e}.

The specification {i_min, i_max, 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

position:

Riffle x between successive elements in a list:

In[1]:=

Out[1]=

Riffle in x and y cyclically:

In[1]:=

Out[1]=

Riffle in x at every 3

position:

In[1]:=

Out[1]=

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

character:

Properties & Relations (1)

Riffle is related to Transpose: