sort.rb

sort.rb

require 'benchmark'

a = (1..100000).map {rand(100000)}

Benchmark.bm(10) do |b|
  b.report("Sort")    { a.sort }
  b.report("Sort by") { a.sort_by {|a| a} }

                 user     system      total        real
Sort         0.030000   0.000000   0.030000 (  0.028076)
Sort by      0.140000   0.000000   0.140000 (  0.138244)

---

require 'benchmark'

a = (1..100000).map {rand(100000)}

Benchmark.bm(10) do |b|
  b.report("Sort")    { a.sort{|x,y| x <=> y} }
  b.report("Sort by") { a.sort_by {|a| a} }

                 user     system      total        real
Sort         0.250000   0.000000   0.250000 (  0.251460)
Sort by      0.130000   0.000000   0.130000 (  0.135658)

---

require 'benchmark'

a = (1..100000).map {rand(100000)}

Benchmark.bm(10) do |b|
  b.report("Sort")    { a.sort{|x,y| x * a <=> y * a} }
  b.report("Sort by") { a.sort_by {|a| a * a} }


                 user     system      total        real
Sort         1.370000   0.000000   1.370000 (  1.369499)
Sort by      0.210000   0.000000   0.210000 (  0.211334)

直接sort快是因为C不用和ruby代码交互的关系吧