Is `map` faster than `each`?

Question

Is map faster at iterating over the array than each? Is there speed difference between the two?

• Map

  result = arr.map {|a| a + 2}
  

• Each

  result = []
  arr.each do |a| 
    result.push(a + 2)
  end
  

Answer 1

I think yes.

I've tried this test

require "benchmark"

n=10000
arr=Array.new(10000,1)
Benchmark.bm do |x|
  #Map
  x.report do
    n.times do
      result = arr.map {|a| a + 2}
    end
  end


  #Each
  x.report do
    n.times do
      result = []
      arr.each do |a|
        result.push(a + 2)
      end
    end
  end
end

And I got this times

       user     system      total        real
   5.790000   0.060000   5.850000 (  5.846956)
   8.210000   0.030000   8.240000 (  8.233849)

Seems like map it's faster

I saw this video http://confreaks.tv/videos/goruco2015-how-to-performance she shows many ruby profiles and tools, if you are interested to improve your performance you will find a lot of tips there.

added

This is a crazy behavior for me!

require "benchmark"

n=10000
arr=Array.new(10000,1)
Benchmark.bm do |x|
  #Map
  x.report do
    n.times do
      result = arr.map {|a| a + 2}
    end
  end
  #Each and push
  x.report do
    n.times do
      result = []
      arr.each do |a|
        result.push(a + 2)
      end
    end
  end

 #Each and <<
  x.report do
    n.times do
      result = []
      arr.each do |a|
        result << (a + 2)
      end
    end
  end
end

and the result

       user     system      total        real
   5.880000   0.080000   5.960000 (  5.949504)
   8.160000   0.010000   8.170000 (  8.164736)
   6.630000   0.010000   6.640000 (  6.632686)

is the operator "<<" faster than method push? I didn't expect that, I thought that was a kind of alias.