inject, merge, each ...

inject_VS_each.rb

#!/usr/bin/env ruby

require 'benchmark'

array = (1..10_000).to_a

m = Benchmark.bm(15) do |x|
  x.report("inject") do
    array.inject({}) do |hash, element|
      hash[element] = element
      hash
    end
  end

  x.report("inject & merge") do
    array.inject({}) do |hash, element|
      hash.merge(element => element)
    end
  end

  x.report("each") do
    hash = {}
    array.each do |element|
      hash[element] = element
    end
    hash
  end
end

puts m


# Output:
#
#                      user     system      total        real
# inject           0.010000   0.000000   0.010000 (  0.011900)
# inject & merge   7.890000   0.020000   7.910000 (  7.905326)
# each             0.000000   0.000000   0.000000 (  0.004576)
#