BUILT-IN MATHEMATICA SYMBOL

MapAt

applies f to the element at position n in expr. If n is negative, the position is counted from the end.

MapAt

applies f to the part of expr at position

.

MapAt

applies f to parts of expr at several positions.

MORE INFORMATION

MapAt or MapAt applies f to the part .

MapAt applies f to parts , , .... »

The list of positions used by MapAt is in the same form as is returned by the function Position. »

MapAt applies f repeatedly to a particular part if that part is mentioned more than once in the list of positions. »

EXAMPLES

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Basic Examples (3)

Map

onto the part at position

:

Map

onto multiple parts:

Map

onto a more deeply nested part:

Map

onto the part at position

:

In[1]:=

Out[1]=

Map

onto multiple parts:

In[1]:=

Out[1]=

Map

onto a more deeply nested part:

In[1]:=

Out[1]=

Scope (5)

A single element of the expression:

Negative numbers count from the end:

Map at a part at level 2:

Map at several elements:

Map at several nested parts:

Generalizations & Extensions (3)

MapAt can be used on expressions with any head:

The function can be mapped onto the heads as well:

Map can be used on sparse arrays:

Applications (4)

Reset an element in a matrix:

Reverse the sign of an element in a matrix:

Enumerate cases with

mapped onto successive elements:

Reverse the color of a cell at a random position at each step:

Properties & Relations (2)

MapAt can use lists of parts returned by Position:

These are the subexpressions returned by Extract:

MapAt applies

repeatedly if a part is mentioned repeatedly: