Benchmarking different ways to transform keys. Run on 100,000 key hash.

hash_transform_keys_benchmarks.rb

class Hash
  # Proposed solution
  def transform_keys
    result = {}
    keys.each do |key|
      result[yield(key)] = self[key]
    end
    result
  end
  def transform_keys!
    keys.each do |key|
      self[yield(key)] = delete(key)
    end
    self
  end

  # Alternate solution
  def transform_keys_with_send(method_name)
    result = {}
    keys.each do |key|
      result[key.send(method_name)] = self[key]
    end
    result
  end
  def transform_keys_with_send!(method_name)
    keys.each do |key|
      self[key.send(method_name)] = delete(key)
    end
    self
  end

  # Original solution
  def stringify_keys
    result = {}
    keys.each do |key|
      result[key.to_s] = self[key]
    end
    result
  end
  def stringify_keys!
    keys.each do |key|
      self[key.to_s] = delete(key)
    end
    self
  end
end


require 'benchmark'


hash = Hash[(1..100000).collect{ |i| [i,i] } ]

puts "stringify_keys"
Benchmark.bmbm(15) do |x|
  x.report("block:")   { hash.transform_keys{ |k| k.to_s} }
  x.report("method send:") { hash.transform_keys_with_send(:to_s) }
  x.report("old way:")  { hash.stringify_keys }
end

puts "\n\n"

puts "stringify_keys!"
Benchmark.bmbm(15) do |x|
  x.report("block:")   { hash.transform_keys!{ |k| k.to_s } }
  x.report("method send:") { hash.transform_keys_with_send!(:to_s) }
  x.report("old way:")  { hash.stringify_keys! }
end

puts "____________"
puts "OTHER BENCHMARKS"
puts "____________"

n = 1_000_000

[ {:k => :v, :a => :b, :c => :d, :e => :f, 'j' => 'k', 'm' => 'n'} ].each do |options|

  Benchmark.bmbm do |bm|
    bm.report "stringify_keys" do
      n.times do
        options.stringify_keys
      end
    end

    bm.report "transform_keys" do
      n.times do
        options.transform_keys(&:to_s)
      end
    end

    bm.report "transform_keys with proper block" do
      n.times do
        options.transform_keys{ |k| k.to_s }
      end
    end

    bm.report "transform_keys_with_send" do
      n.times do
        options.transform_keys_with_send(:to_s)
      end
    end

    bm.report "stringify_keys!" do
      n.times do
        options.stringify_keys!
      end
    end

    bm.report "transform_keys!" do
      n.times do
        options.transform_keys!(&:to_s)
      end
    end

    bm.report "transform_keys with proper block!" do
      n.times do
        options.transform_keys!{ |k| k.to_s }
      end
    end

    bm.report "transform_keys_with_send!" do
      n.times do
        options.transform_keys_with_send!(:to_s)
      end
    end
  end
end

marks_results.txt

stringify_keys
Rehearsal ---------------------------------------------------
block:            0.150000   0.020000   0.170000 (  0.157368)
method send:      0.160000   0.010000   0.170000 (  0.170694)
old way:          0.160000   0.000000   0.160000 (  0.160916)
------------------------------------------ total: 0.500000sec

                      user     system      total        real
block:            0.140000   0.000000   0.140000 (  0.141677)
method send:      0.130000   0.000000   0.130000 (  0.135184)
old way:          0.140000   0.000000   0.140000 (  0.134680)


stringify_keys!
Rehearsal ---------------------------------------------------
block:            0.170000   0.010000   0.180000 (  0.173217)
method send:      0.150000   0.000000   0.150000 (  0.156781)
old way:          0.140000   0.000000   0.140000 (  0.132320)
------------------------------------------ total: 0.470000sec

                      user     system      total        real
block:            0.140000   0.000000   0.140000 (  0.136851)
method send:      0.120000   0.000000   0.120000 (  0.123499)
old way:          0.120000   0.010000   0.130000 (  0.125058)
____________
OTHER BENCHMARKS
____________
Rehearsal ---------------------------------------------------------------------
stringify_keys                      5.830000   0.080000   5.910000 (  5.919836)
transform_keys                      6.330000   0.080000   6.410000 (  6.423611)
transform_keys with proper block    6.170000   0.080000   6.250000 (  6.246085)
transform_keys_with_send            5.940000   0.080000   6.020000 (  6.030339)
stringify_keys!                     3.930000   0.040000   3.970000 (  3.967233)
transform_keys!                     4.270000   0.030000   4.300000 (  4.311692)
transform_keys with proper block!   4.150000   0.030000   4.180000 (  4.185313)
transform_keys_with_send!           3.870000   0.040000   3.910000 (  3.903076)
----------------------------------------------------------- total: 40.950000sec

                                        user     system      total        real
stringify_keys                      4.770000   0.100000   4.870000 (  4.875548)
transform_keys                      5.230000   0.100000   5.330000 (  5.340638)
transform_keys with proper block    4.970000   0.090000   5.060000 (  5.076670)
transform_keys_with_send            4.990000   0.100000   5.090000 (  5.083732)
stringify_keys!                     3.720000   0.020000   3.740000 (  3.737684)
transform_keys!                     4.070000   0.020000   4.090000 (  4.102100)
transform_keys with proper block!   3.990000   0.030000   4.020000 (  4.019291)
transform_keys_with_send!           3.820000   0.020000   3.840000 (  3.847108)