map

Invokes block once for each element of self. Creates a new array containing the values returned by the block. See also Enumerable#collect.

If no block is given, an enumerator is returned instead.

a = [ "a", "b", "c", "d" ]
a.collect {|x| x + "!" }   #=> ["a!", "b!", "c!", "d!"]
a                          #=> ["a", "b", "c", "d"]