result.txt

(Ruby 2.2.2)
user     system      total        real

Scale: 1
shuffle and take  0.010000   0.000000   0.010000 (  0.007580)
sample       0.000000   0.000000   0.000000 (  0.004182)

Scale: 10
shuffle and take  0.010000   0.000000   0.010000 (  0.011985)
sample       0.020000   0.000000   0.020000 (  0.016216)

Scale: 100
shuffle and take  0.040000   0.010000   0.050000 (  0.052012)
sample       0.010000   0.000000   0.010000 (  0.013686)

Scale: 1000
shuffle and take  0.360000   0.090000   0.450000 (  0.597210)
sample       0.000000   0.000000   0.000000 (  0.006961)

Scale: 10000
shuffle and take  2.080000   0.140000   2.220000 (  2.247604)
sample       0.000000   0.000000   0.000000 (  0.005969)

Scale: 100000
shuffle and take 22.120000   2.120000  24.240000 ( 24.661264)
sample       0.000000   0.000000   0.000000 (  0.007182)

Scale: 1000000
shuffle and take 370.370000  22.020000 392.390000 (402.516775)
sample       0.010000   0.000000   0.010000 (  0.007679)

shuffle_and_take_vs_sample.rb

require 'benchmark'

Benchmark.bm(10) do |x|
  7.times do |n|
      scale = 10 ** n
      puts "\nScale: #{scale}"

      data = Array.new(scale).map { Random.rand() }
      x.report("shuffle and take") do
        10000.times do
          a = data.shuffle.take(10)
        end
      end

      data = Array.new(scale).map { Random.rand() }
      x.report("sample") do
        10000.times do
          a = data.sample(10)
        end
      end
  end
end