sorting_an_array_in_descending_order.rb

#!/usr/bin/env ruby

require 'benchmark'

ary = []
1000.times {
  ary << {:bar => rand(1000)}
}

n = 500
Benchmark.bm(20) do |x|
  x.report("sort")               { n.times { ary.sort{ |a,b| b[:bar] <=> a[:bar] } } }
  x.report("sort reverse")       { n.times { ary.sort{ |a,b| a[:bar] <=> b[:bar] }.reverse } }
  x.report("sort_by -a[:bar]")   { n.times { ary.sort_by{ |a| -a[:bar] } } }
  x.report("sort_by a[:bar]*-1") { n.times { ary.sort_by{ |a| a[:bar]*-1 } } }
  x.report("sort_by.reverse!")   { n.times { ary.sort_by{ |a| a[:bar] }.reverse } }
end

#                           user     system      total        real
#sort                   0.530000   0.000000   0.530000 (  0.539872)
#sort reverse           0.550000   0.000000   0.550000 (  0.551648)
#sort_by -a[:bar]       0.240000   0.010000   0.250000 (  0.239292)
#sort_by a[:bar]*-1     0.230000   0.000000   0.230000 (  0.230042)
#sort_by.reverse!       0.220000   0.000000   0.220000 (  0.226368)