Map 
Map[f,expr] or f/@expr
applies f to each element on the first level in expr.
Map[f,expr,levelspec]
applies f to parts of expr specified by levelspec.
Details and Options

- Map uses standard level specifications:
-
n levels 1 through n Infinity levels 1 through Infinity {n} level n only {n1,n2} levels n1 through n2 - The default value for levelspec in Map is {1}.
- A positive level n consists of all parts of expr specified by n indices.
- A negative level -n consists of all parts of expr with depth n.
- Level –1 consists of numbers, symbols, and other objects that do not have subparts.
- Level 0 corresponds to the whole expression.
- With the option setting Heads->True, Map includes heads of expressions and their parts.
- Map always effectively constructs a complete new expression and then evaluates it.
- If expr is an Association object, Map[f,expr] applies f to the values in the association.
- If expr is a SparseArray object, Map[f,expr] applies f to the values or subarrays that appear in expr.
- Map[f][expr] is equivalent to Map[f,expr].
Examples
open allclose allBasic Examples (8)
Map a function over values in Association:
Map at the second level of a nested Association:
Map at several levels in an Association:
Scope (6)
Generalizations & Extensions (4)
Applications (4)
Properties & Relations (5)
Possible Issues (1)
Map by default starts at level 1, so does not apply the function to the whole expression:
Text
Wolfram Research (1988), Map, Wolfram Language function, https://reference.wolfram.com/language/ref/Map.html (updated 2014).
BibTeX
BibLaTeX
CMS
Wolfram Language. 1988. "Map." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2014. https://reference.wolfram.com/language/ref/Map.html.
APA
Wolfram Language. (1988). Map. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Map.html