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MapAt

Usage

• MapAt[f, expr, n] applies f to the element at position n in expr. If n is negative, the position is counted from the end.
• MapAt[f, expr, {i, j, ... }] applies f to the part of expr at position {i, j, ... }.
• MapAt[f, expr, {{ , , ... }, { , , ... }, ... }] applies f to parts of expr at several positions.


Notes

• Example: MapAt[f, a, b, c , 2]LongRightArrow .
• MapAt[f, a, b, c, d , 1 , 4 ]LongRightArrow .
• MapAt[f, expr, {i, j, ... }] or MapAt[f, expr, {{i, j, ... }}] applies f to the part expr[[i, j, ... ]].
• MapAt[f, expr, {{ , , ... }, { , , ... }, ... }] applies f to parts expr[[ , , ... ]], expr[[ , , ... ]], ... .
• 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.
• Example: MapAt[f, a, b, c , 1 , 3 , 1 ]LongRightArrow .
• See Section 2.2.4.
• See also: ReplacePart, Delete, FlattenAt.
• New in Version 1.
Further Examples


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