Question

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Ruby – What is the difference between map, each and collect?

I have looked in Ruby-Doc also but i cant understand the difference between

map
each

iterators.It would be great if you could give an example and explain.

Answer 1

each simply iterates over the given enumerable, running the block for each value. It discards the return value of the block, and each simply returns the original object it was called on:

[1, 2, 3].each do |x|
  x + 1
end  # => [1, 2, 3]

This is simply a nicer, more universal way of doing a traditional iterating for loop, and each is much preferred over for loops in Ruby (in fact, I don’t think I’ve ever used a for loop in Ruby).

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map, however, iterates over each element, using the return value of the block to populate a new array at each respective index and return that new array:

[1, 2, 3].map do |x|
  x + 1
end  # => [2, 3, 4]

So it “maps” each element to a new one using the block given, hence the name “map”. Note that neither each nor map themselves modify the original collection. This is a concise, functional alternative to creating an array and pushing to it in an iterative loop.