Question
This question already has answers here :
[what's different between each and collect method in Ruby [duplicate]](/questions/5347949/whats-different-between-each-and-collect- method-in-ruby) (7 answers)
Closed 9 years ago.
In Ruby, is there any difference between the functionalities of each, map,
and collect?
Answer
each is different from map and collect, but map and collect are the
same (technically map is an alias for collect, but in my experience map
is used a lot more frequently).
each performs the enclosed block for each element in the (Enumerable)
receiver:
[1,2,3,4].each {|n| puts n*2}
# Outputs:
# 2
# 4
# 6
# 8
map and collect produce a new Array containing the results of the block
applied to each element of the receiver:
[1,2,3,4].map {|n| n*2}
# => [2,4,6,8]
There's also map! / collect! defined on Arrays; they modify the receiver
in place:
a = [1,2,3,4]
a.map {|n| n*2} # => [2,4,6,8]
puts a.inspect # prints: "[1,2,3,4]"
a.map! {|n| n+1}
puts a.inspect # prints: "[2,3,4,5]"
