Benchmarking some simple counting functions in Ruby. ( http://m635j520.blogspot.fr/2013/01/counting-in-ruby-revisited-benchmarked.html )

count_benchmarking.rb

require 'benchmark'
require 'benchmark/ips'

array = []
1000.times { array << rand(1000) }
N = 10000

module Enumerable
  def count_by_function function
    map = Hash.new(0)
    self.each { |e| map[e.send(function)] += 1 }
    map
  end

  def count_by_block (&block)
    Hash[ self.group_by { |e| yield e }.map { |key, list| [key, list.length] } ]
  end
end

Benchmark.bm do |r|
  r.report("count_by_function ") do
    N.times { array.count_by_function (:even?) }
  end

  r.report("count_by_block ") do
    N.times { array.count_by_block { |e| e.even? } }
  end
end

Benchmark.ips do |r|
  r.report("count_by_function ") do
    array.count_by_function (:even?)
  end

  r.report("count_by_block ") do
    array.count_by_block { |e| e.even? }
  end
end

#                     user       system     total       real
# count_by_function   2.950000   0.000000   2.950000 (  2.956958)
# count_by_block      2.350000   0.000000   2.350000 (  2.352997)
#
# Calculating -------------------------------------
#   count_by_function        326 i/100ms
#      count_by_block        418 i/100ms
# -------------------------------------------------
#   count_by_function      3243.3 (±2.8%) i/s -      16300 in   5.029924s
#      count_by_block      4256.7 (±1.5%) i/s -      21318 in   5.009192s