Sorting arrays of related objects

coarrays.rb

require 'benchmark'

N = 100_000

[3, 5, 10].each do |array_size|

  terms = []
  arr2 = []
  array_size.times do |n|
    terms << {:id => n, :name => "term#{n}", :version => 1}
    arr2 << {:term_id => n, :name => "assoc#{n}"}
  end

  # Randomize them
  terms.sort_by! { rand }
  arr2.sort_by! { rand }

  puts "Benchmark for arrays with #{array_size} items:"
  puts "terms = #{terms.inspect}"
  puts "arr2 = #{arr2.inspect}"
  Benchmark.bm(10) do |x|
    x.report('find_index:') do 
      N.times do
        arr2.sort_by {|o| terms.find_index {|a| o[:term_id] == a[:id]}}
      end
    end
    x.report('gen_lookup:') do
      N.times do
        lookup = {}
        terms.each_with_index { |t, idx| lookup[t[:id]] = idx}
        arr2.sort_by {|o| lookup[o[:term_id]]}
      end
    end

  end
end

results.txt

Benchmark for arrays with 3 items:
terms = [{:id=>2, :name=>"term2", :version=>1}, {:id=>1, :name=>"term1", :version=>1}, {:id=>0, :name=>"term0", :version=>1}]
arr2 = [{:term_id=>2, :name=>"assoc2"}, {:term_id=>1, :name=>"assoc1"}, {:term_id=>0, :name=>"assoc0"}]
                 user     system      total        real
find_index:  0.280000   0.000000   0.280000 (  0.282137)
gen_lookup:  0.400000   0.000000   0.400000 (  0.398467)
Benchmark for arrays with 5 items:
terms = [{:id=>3, :name=>"term3", :version=>1}, {:id=>4, :name=>"term4", :version=>1}, {:id=>0, :name=>"term0", :version=>1}, {:id=>1, :name=>"term1", :version=>1}, {:id=>2, :name=>"term2", :version=>1}]
arr2 = [{:term_id=>2, :name=>"assoc2"}, {:term_id=>1, :name=>"assoc1"}, {:term_id=>0, :name=>"assoc0"}, {:term_id=>3, :name=>"assoc3"}, {:term_id=>4, :name=>"assoc4"}]
                 user     system      total        real
find_index:  0.470000   0.000000   0.470000 (  0.471214)
gen_lookup:  0.500000   0.010000   0.510000 (  0.510521)
Benchmark for arrays with 10 items:
terms = [{:id=>5, :name=>"term5", :version=>1}, {:id=>7, :name=>"term7", :version=>1}, {:id=>9, :name=>"term9", :version=>1}, {:id=>3, :name=>"term3", :version=>1}, {:id=>6, :name=>"term6", :version=>1}, {:id=>8, :name=>"term8", :version=>1}, {:id=>1, :name=>"term1", :version=>1}, {:id=>0, :name=>"term0", :version=>1}, {:id=>4, :name=>"term4", :version=>1}, {:id=>2, :name=>"term2", :version=>1}]
arr2 = [{:term_id=>9, :name=>"assoc9"}, {:term_id=>5, :name=>"assoc5"}, {:term_id=>1, :name=>"assoc1"}, {:term_id=>6, :name=>"assoc6"}, {:term_id=>4, :name=>"assoc4"}, {:term_id=>0, :name=>"assoc0"}, {:term_id=>8, :name=>"assoc8"}, {:term_id=>3, :name=>"assoc3"}, {:term_id=>7, :name=>"assoc7"}, {:term_id=>2, :name=>"assoc2"}]
                 user     system      total        real
find_index:  1.240000   0.000000   1.240000 (  1.240375)
gen_lookup:  0.870000   0.010000   0.880000 (  0.880777)
Benchmark for arrays with 30 items:
terms = [{:id=>6, :name=>"term6", :version=>1}, {:id=>20, :name=>"term20", :version=>1}, {:id=>19, :name=>"term19", :version=>1}, {:id=>29, :name=>"term29", :version=>1}, {:id=>24, :name=>"term24", :version=>1}, {:id=>4, :name=>"term4", :version=>1}, {:id=>5, :name=>"term5", :version=>1}, {:id=>3, :name=>"term3", :version=>1}, {:id=>11, :name=>"term11", :version=>1}, {:id=>18, :name=>"term18", :version=>1}, {:id=>0, :name=>"term0", :version=>1}, {:id=>28, :name=>"term28", :version=>1}, {:id=>23, :name=>"term23", :version=>1}, {:id=>27, :name=>"term27", :version=>1}, {:id=>1, :name=>"term1", :version=>1}, {:id=>22, :name=>"term22", :version=>1}, {:id=>9, :name=>"term9", :version=>1}, {:id=>8, :name=>"term8", :version=>1}, {:id=>14, :name=>"term14", :version=>1}, {:id=>17, :name=>"term17", :version=>1}, {:id=>10, :name=>"term10", :version=>1}, {:id=>26, :name=>"term26", :version=>1}, {:id=>21, :name=>"term21", :version=>1}, {:id=>2, :name=>"term2", :version=>1}, {:id=>25, :name=>"term25", :version=>1}, {:id=>7, :name=>"term7", :version=>1}, {:id=>13, :name=>"term13", :version=>1}, {:id=>12, :name=>"term12", :version=>1}, {:id=>16, :name=>"term16", :version=>1}, {:id=>15, :name=>"term15", :version=>1}]
arr2 = [{:term_id=>11, :name=>"assoc11"}, {:term_id=>15, :name=>"assoc15"}, {:term_id=>19, :name=>"assoc19"}, {:term_id=>23, :name=>"assoc23"}, {:term_id=>5, :name=>"assoc5"}, {:term_id=>18, :name=>"assoc18"}, {:term_id=>21, :name=>"assoc21"}, {:term_id=>0, :name=>"assoc0"}, {:term_id=>12, :name=>"assoc12"}, {:term_id=>27, :name=>"assoc27"}, {:term_id=>29, :name=>"assoc29"}, {:term_id=>1, :name=>"assoc1"}, {:term_id=>3, :name=>"assoc3"}, {:term_id=>26, :name=>"assoc26"}, {:term_id=>2, :name=>"assoc2"}, {:term_id=>13, :name=>"assoc13"}, {:term_id=>20, :name=>"assoc20"}, {:term_id=>25, :name=>"assoc25"}, {:term_id=>22, :name=>"assoc22"}, {:term_id=>9, :name=>"assoc9"}, {:term_id=>24, :name=>"assoc24"}, {:term_id=>7, :name=>"assoc7"}, {:term_id=>10, :name=>"assoc10"}, {:term_id=>28, :name=>"assoc28"}, {:term_id=>16, :name=>"assoc16"}, {:term_id=>17, :name=>"assoc17"}, {:term_id=>4, :name=>"assoc4"}, {:term_id=>6, :name=>"assoc6"}, {:term_id=>14, :name=>"assoc14"}, {:term_id=>8, :name=>"assoc8"}]
                 user     system      total        real
find_index:  8.440000   0.010000   8.450000 (  8.461052)
gen_lookup:  2.500000   0.040000   2.540000 (  2.540562)