Roman numerals - comparing two implementations

comp_results_via_irb.rb

2.3.0 :001 > require "benchmark/ips"
 => true
2.3.0 :002 > class Fixnum
2.3.0 :003?>     VERSION = 1

  ROMAN_NUMERALS = { 'M'  => 1000,
                     'CM' => 900,
                     'D'  => 500,
                     'CD' => 400,
                     'C'  => 100,
                     'XC' => 90,
                     'L'  => 50,
                     'XL' => 40,
                     'X'  => 10,
                     'IX' => 9,
                     'V'  => 5,
                     'IV' => 4,
                     'I'  => 1 }.freeze

  def to_roman_fast
    return "" if zero?
    letter, num = ROMAN_NUMERALS.detect { |roman_numeral, number| number <= self }
    rest = self - num
    "#{letter}#{rest.to_roman_fast}"
  end

  def to_roman_slow
    number_to_convert = self

    ROMAN_NUMERALS.each_with_object("") do |(roman_numeral, numeric_equivalent), roman_equivalent|
      next if numeric_equivalent > number_to_convert

      quotient, remainder = number_to_convert.divmod(numeric_equivalent)
      number_to_convert = remainder
      roman_equivalent << roman_numeral * quotien2.3.0 :004?>
2.3.0 :005 >       ROMAN_NUMERALS = { 'M'  => 1000,
2.3.0 :006 >                            'CM' => 900,
2.3.0 :007 >                            'D'  => 500,
2.3.0 :008 >                            'CD' => 400,
2.3.0 :009 >                            'C'  => 100,
2.3.0 :010 >                            'XC' => 90,
2.3.0 :011 >                            'L'  => 50,
2.3.0 :012 >                            'XL' => 40,
2.3.0 :013 >                            'X'  => 10,
2.3.0 :014 >                            'IX' => 9,
2.3.0 :015 >                            'V'  => 5,
2.3.0 :016 >                            'IV' => 4,
2.3.0 :017 >                            'I'  => 1 }.freeze
2.3.0 :018?>
2.3.0 :019 >       def to_roman_fast
2.3.0 :020?>         return "" if zero?
2.3.0 :021?>         letter, num = ROMAN_NUMERALS.detect { |roman_numeral, number| number <= self }
2.3.0 :022?>         rest = self - num
2.3.0 :023?>         "#{letter}#{rest.to_roman_fast}"
2.3.0 :024?>       end
2.3.0 :025?>
2.3.0 :026 >       def to_roman_slow
2.3.0 :027?>         number_to_convert = self
2.3.0 :028?>
2.3.0 :029 >           ROMAN_NUMERALS.each_with_object("") do |(roman_numeral, numeric_equivalent), roman_equivalent|
2.3.0 :030 >               next if numeric_equivalent > number_to_convert
2.3.0 :031?>
2.3.0 :032 >               quotient, remainder = number_to_convert.divmod(numeric_equivalent)
2.3.0 :033?>             number_to_convert = remainder
2.3.0 :034?>             roman_equivalent << roman_numeral * quotient
2.3.0 :035?>           end
2.3.0 :036?>       end
2.3.0 :037?>
2.3.0 :038 >     end
 => :to_roman_slow
2.3.0 :039 > Benchmark.ips do |x|
2.3.0 :040 >       x.report("fast code description") { 23.to_roman_fast }
2.3.0 :041?>     x.report("slow code description") { 23.to_roman_slow }
2.3.0 :042?>     x.compare!
2.3.0 :043?>   end
Warming up --------------------------------------
fast code description
                         8.186k i/100ms
slow code description
                        22.396k i/100ms
Calculating -------------------------------------
fast code description
                         86.120k (± 7.1%) i/s -    433.858k
slow code description
                        296.277k (± 6.8%) i/s -      1.478M

Comparison:
slow code description:   296276.6 i/s
fast code description:    86120.3 i/s - 3.44x slower

 => #<Benchmark::IPS::Report:0x007fbd1493f818 @entries=[#<Benchmark::IPS::Report::Entry:0x007fbd13858e78 @label="fast code description", @microseconds=5063694.477081299, @iterations=433858, @ips=86120.27317565453, @ips_sd=6130, @measurement_cycle=8186, @show_total_time=false>, #<Benchmark::IPS::Report::Entry:0x007fbd138b32d8 @label="slow code description", @microseconds=5013072.0138549805, @iterations=1478136, @ips=296276.63372336526, @ips_sd=20182, @measurement_cycle=22396, @show_total_time=false>], @data=nil>
2.3.0 :044 >

exercises_compared.rb

Impl 1 - http://exercism.io/submissions/61ad4a5a70ab4194aaf09875997da322
Impl 2 - (my implementation took quite a bit of insipration from - http://exercism.io/submissions/525704159fcfeabc2200023a)

roman_num_code_used_for_comp.rb

class Fixnum
  VERSION = 1

  ROMAN_NUMERALS = { 'M'  => 1000,
                     'CM' => 900,
                     'D'  => 500,
                     'CD' => 400,
                     'C'  => 100,
                     'XC' => 90,
                     'L'  => 50,
                     'XL' => 40,
                     'X'  => 10,
                     'IX' => 9,
                     'V'  => 5,
                     'IV' => 4,
                     'I'  => 1 }.freeze

  def to_roman_fast
    return "" if zero?
    letter, num = ROMAN_NUMERALS.detect { |roman_numeral, number| number <= self }
    rest = self - num
    "#{letter}#{rest.to_roman_fast}"
  end

  def to_roman_slow
    number_to_convert = self

    ROMAN_NUMERALS.each_with_object("") do |(roman_numeral, numeric_equivalent), roman_equivalent|
      next if numeric_equivalent > number_to_convert

      quotient, remainder = number_to_convert.divmod(numeric_equivalent)
      number_to_convert = remainder
      roman_equivalent << roman_numeral * quotient
    end
  end

end