today's bench

find-max-key-in-condition.rb

require 'benchmark'
require 'active_support/all'

n = ARGV[0]&.to_i || 50000
m = ARGV[1]&.to_i || 20

arr = Array.new(m){|i| [i, [:a, :b, :c, :d].sample] }.shuffle.to_h
Benchmark.bmbm do |b|
  b.report("1:") { n.times{ arr.select{|_,v| v == :a }.max&.first }}
  b.report("2:") { n.times{ arr.each_with_object([]){|(k,v),o| o << k if v == :a }.max }}
  b.report("3:") { n.times{ a = 0; arr.each{|k,v| a = k if v == :a && a < k }; a == 0 ? nil : a }}
  b.report("4:") { n.times{ arr.sort.reverse_each.find{|k,v| v == :a }&.first }}
  b.report("5:") { n.times{ arr.sort_by{|k,v| -k }.find{|k,v| v == :a }&.first }}
end

__END__
Rehearsal --------------------------------------
1:   0.190000   0.000000   0.190000 (  0.191267)
2:   0.180000   0.010000   0.190000 (  0.185720)
3:   0.080000   0.000000   0.080000 (  0.085030)
4:   0.970000   0.000000   0.970000 (  0.988984)
5:   0.430000   0.010000   0.440000 (  0.439052)
----------------------------- total: 1.870000sec

         user     system      total        real
1:   0.180000   0.000000   0.180000 (  0.189173)
2:   0.180000   0.000000   0.180000 (  0.185014)
3:   0.090000   0.000000   0.090000 (  0.091285)
4:   0.990000   0.010000   1.000000 (  1.003560)
5:   0.420000   0.000000   0.420000 (  0.426253)