Ruby 1.9.0 group_by benchmark

gistfile1.rb

require 'rubygems'
require 'activesupport'
require 'benchmark'
include Benchmark

class T
  attr_accessor :date, :count
  def initialize(_date,_count)
    @count = _count
    @date = _date
  end
end


def fill_array(n)
  a = []
  random_dates = n / 5
  n.times { |x| a << T.new(rand(random_dates).days.ago,x) }
  return a
end

(2..5).each do |p|
  n = 10**p
  puts "=== 10^#{p} ==="
  array = []
  benchmark do |x|
    x.report("filling array     : ") { array = fill_array(n) }
    x.report("group_by (Time)   : ") { array.group_by { |r| r.date } }
    x.report("group_by (Date)   : ") { array.group_by { |r| r.date.to_date } }
    x.report("group_by (String) : ") { array.group_by { |r| r.date.to_date.to_s } }
  end
end