[観察日記 2018-02-14 - なるせにっき](http://naruse.hateblo.jp/entry/2018/02/14/221859) 「配列の全ての要素が等しいか否か」のベンチマークスクリプトと結果

benchmark-same-all.log

% ruby -v benchmark-same-all.rb
ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-linux]
 ["a","a",...] user     system      total        real
all?        0.490852   0.000000   0.490852 (  0.492231)
uniq.size   0.249663   0.039904   0.289567 (  0.290653)
lazy cnt    0.387460   0.000005   0.387465 (  0.388847)
lazy t2cnt  0.409444   0.000000   0.409444 (  0.410681)
each_cons   1.134791   0.000000   1.134791 (  1.137745)
lazy one?   0.394611   0.000000   0.394611 (  0.395936)
rotate      0.023589   0.011946   0.035535 (  0.035795)
range       0.006502   0.000000   0.006502 (  0.006506)
map all?        2.558119   0.023979   2.582098 (  2.587691)
map uniq.size   2.380210   0.104611   2.484821 (  2.491208)
map lazy cnt    3.187991   0.011623   3.199614 (  3.221779)
map lazy t2cnt  3.043720   0.000000   3.043720 (  3.047949)
map each_cons   2.801011   0.019936   2.820947 (  2.821781)
map lazy one?   2.918080   0.000000   2.918080 (  2.918291)
map rotate      1.434895   0.031964   1.466859 (  1.467404)
map range       1.574584   0.036031   1.610615 (  1.610860)
 ["b","a",...] user     system      total        real
all?        0.000009   0.000000   0.000009 (  0.000005)
uniq.size   0.524196   0.032005   0.556201 (  0.556199)
lazy cnt    0.390134   0.000000   0.390134 (  0.390147)
lazy t2cnt  0.000030   0.000000   0.000030 (  0.000029)
each_cons   0.000007   0.000000   0.000007 (  0.000006)
lazy one?   0.000008   0.000000   0.000008 (  0.000007)
rotate      0.390551   0.011957   0.402508 (  0.402512)
range       0.000005   0.000000   0.000005 (  0.000004)
map all?        0.000006   0.000000   0.000006 (  0.000006)
map uniq.size   1.914109   0.056030   1.970139 (  1.970635)
map lazy cnt    3.144191   0.004001   3.148192 (  3.148900)
map lazy t2cnt  0.000040   0.000000   0.000040 (  0.000039)
map each_cons   1.471266   0.000000   1.471266 (  1.471515)
map lazy one?   0.000019   0.000000   0.000019 (  0.000019)
map rotate      1.408608   0.023948   1.432556 (  1.432553)
map range       1.762782   0.000037   1.762819 (  1.763363)

benchmark-same-all.rb

#!/usr/bin/env ruby

require "benchmark"

def run(n, element)
  ary = Array.new(n) { element }
  [element, element.next].each do |first_element|
    ary[0] = first_element
    title = "[#{ary[0].inspect},#{ary[1].inspect},...]"
    caption = title + Benchmark::CAPTION.sub(/\A\s+/, " ")
    Benchmark.benchmark(caption) do |x|
      x.report("all?      ") do
        ary.all? {|e| e == ary[0] }
      end
      x.report("uniq.size ") do
        ary.uniq.size == 1
      end
      x.report("lazy cnt  ") do
        ary.lazy.uniq.count == 1
      end
      x.report("lazy t2cnt") do
        ary.lazy.uniq.take(2).count == 1
      end
      x.report("each_cons ") do
        ary.each_cons(2).all? { |a,b| a == b }
      end
      x.report("lazy one? ") do
        ary.lazy.uniq.one?
      end
      x.report("rotate    ") do
        ary.rotate == ary
      end
      x.report("range     ") do
        ary[0..-2] == ary[1..-1]
      end
      x.report("map all?      ") do
        ary.all? {|e| e.next == ary[0].next }
      end
      x.report("map uniq.size ") do
        ary.map(&:next).uniq.size == 1
      end
      x.report("map lazy cnt  ") do
        ary.lazy.map(&:next).uniq.count == 1
      end
      x.report("map lazy t2cnt") do
        ary.lazy.map(&:next).uniq.take(2).count == 1
      end
      x.report("map each_cons ") do
        ary.map(&:next).each_cons(2).all? { |a,b| a == b }
      end
      x.report("map lazy one? ") do
        ary.lazy.map(&:next).uniq.one?
      end
      x.report("map rotate    ") do
        mapped_ary = ary.map(&:next)
        mapped_ary.rotate == mapped_ary
      end
      x.report("map range     ") do
        mapped_ary = ary.map(&:next)
        mapped_ary[0..-2] == mapped_ary[1..-1]
      end
    end
  end
end

run(10 ** 7, "a")