gistfile1.rb

require "rubygems"
require "rbench"
require "set"

RANGE = (1..1000)
ARRAY = RANGE.to_a
SET   = Set.new(ARRAY)
HASH  = ARRAY.inject({}) {|m, x| m[x] = true; m}

WORST_CASE_COMPLEXITY = ARRAY.size + 1

RBench.run(50_000) do
  column :one,   :title => 'Array'
  column :two,   :title => 'Set'
  column :three, :title => 'Range'
  column :four,  :title => 'Hash'

  report "Which is fastest for misses?" do
    one {   ARRAY.include?(WORST_CASE_COMPLEXITY) }
    two {   SET.include?(WORST_CASE_COMPLEXITY)   }
    three { RANGE.include?(WORST_CASE_COMPLEXITY) }
    four  { HASH.include?(WORST_CASE_COMPLEXITY) }
  end

  report "Which is fastest for hits?" do
    one {   ARRAY.include?(1) }
    two {   SET.include?(1)   }
    three { RANGE.include?(1) }
    four  { HASH.include?(1) }
  end
end

__END__
                                       Array |     Set |   Range |    Hash |
----------------------------------------------------------------------------
Which is fastest for misses?           2.237 |   0.016 |   0.016 |   0.009 |
Which is fastest for hits?             0.007 |   0.015 |   0.017 |   0.008 |