Benchmarking sampling of a hash

benchmark.rb

require "benchmark"

n    = 10000
arr  = (1..1000).to_a
zip  = arr.zip arr
hash = Hash[zip]

Benchmark.bm do |x|
  x.report("%-30s" %["sampling array"]) { n.times do
      arr.sample
  end }
  x.report("%-30s" %["creating hash"]) { n.times do
      Hash[zip]
  end }
  x.report("%-30s" %["sampling hash with #[]   1"]) { n.times do
      Hash[ hash.to_a.sample(1) ]
  end }
  x.report("%-30s" %["sampling hash with #to_h 1"]) { n.times do
      hash.to_a.sample(1).to_h
  end }
  x.report("%-30s" %["sampling hash with #[]   10"]) { n.times do
      Hash[ hash.to_a.sample(10) ]
  end }
  x.report("%-30s" %["sampling hash with #to_h 10"]) { n.times do
      hash.to_a.sample(10).to_h
  end }
  x.report("%-30s" %["sampling hash with #[]   100"]) { n.times do
      Hash[ hash.to_a.sample(100) ]
  end }
  x.report("%-30s" %["sampling hash with #to_h 100"]) { n.times do
      hash.to_a.sample(100).to_h
  end }
  x.report("%-30s" %["sampling hash with #[]   1000"]) { n.times do
      Hash[ hash.to_a.sample(1000) ]
  end }
  x.report("%-30s" %["sampling hash with #to_h 1000"]) { n.times do
      hash.to_a.sample(1000).to_h
  end }
end

results

                                user     system      total        real
sampling array                  0.000000   0.000000   0.000000 (  0.000946)
creating hash                   2.730000   0.130000   2.860000 (  2.865713)
sampling hash with #[]   1      0.790000   0.010000   0.800000 (  0.789821)
sampling hash with #to_h 1      0.730000   0.000000   0.730000 (  0.735309)
sampling hash with #[]   10     0.770000   0.000000   0.770000 (  0.764275)
sampling hash with #to_h 10     0.770000   0.000000   0.770000 (  0.772692)
sampling hash with #[]   100    1.020000   0.000000   1.020000 (  1.021916)
sampling hash with #to_h 100    1.020000   0.000000   1.020000 (  1.021014)
sampling hash with #[]   1000   3.530000   0.010000   3.540000 (  3.536519)
sampling hash with #to_h 1000   3.540000   0.000000   3.540000 (  3.541142)