Benchmark: each_with_object vs map!

each_with_object_vs_map.rb

require 'benchmark/ips'

array = (1..10_000).to_a

Benchmark.ips do |x|
  x.report('each_with_object') { array.each_with_object([]) { |i,a| a << (i * 2) } }
  x.report('map') { array.map { |i| i * 2 } }
  x.report('map!') { array.map! { |i| i * 2 } }
  x.report('reduse') { array.reduce([]) { |a,i| a << i * 2 } }
  x.compare!
end

# Warming up --------------------------------------
#     each_with_object    75.000  i/100ms
#                  map   132.000  i/100ms
#                 map!    24.000  i/100ms
#               reduse    17.000  i/100ms
# Calculating -------------------------------------
#     each_with_object    156.681  (±19.8%) i/s -    825.000  in   5.563924s
#                  map    201.255  (± 4.0%) i/s -      1.056k in   5.254692s
#                 map!    179.438  (±11.7%) i/s -    888.000
#               reduse    165.944  (± 5.4%) i/s -    833.000
#
# Comparison:
#                  map:      201.3 i/s
#                 map!:      179.4 i/s - 1.12x slower
#               reduse:      165.9 i/s - 1.21x slower
#     each_with_object:      156.7 i/s - 1.28x slower