partition_odd_end_even.rb

require 'benchmark'
require 'benchmark/ips'

Benchmark.ips do |r|
  r.report("group_by") do
    (0..1000).group_by { |w| w % 2 == 0 }.values
  end

  EVEN = 0
  ODD = 1
  r.report("dumb") do
    (0..1000).inject(Array.new(2) { [] }) do |numbers, number|
      numbers[number % 2 == 0 ? EVEN : ODD] << number
      numbers
    end
  end

  r.report("partition") do
    (0..1000).partition(&:even?)
  end
end

# Calculating -------------------------------------
#             group_by       621 i/100ms
#                 dumb       529 i/100ms
#            partition       915 i/100ms
# -------------------------------------------------
#             group_by     6375.8 (±2.1%) i/s -      32292 in   5.067062s
#                 dumb     5791.0 (±11.0%) i/s -      28566 in   5.003636s
#            partition     9492.3 (±11.4%) i/s -      47580 in   5.094445s