module RailsGuides::Levenshtein

Public Class Methods

distance(str1, str2) click to toggle source

This code is based directly on the Text gem implementation Returns a value representing the “cost” of transforming str1 into str2

# File guides/rails_guides/levenshtein.rb, line 5
def self.distance str1, str2
  s = str1
  t = str2
  n = s.length
  m = t.length

  return m if (0 == n)
  return n if (0 == m)

  d = (0..m).to_a
  x = nil

  str1.each_char.each_with_index do |char1,i|
    e = i+1

    str2.each_char.each_with_index do |char2,j|
      cost = (char1 == char2) ? 0 : 1
      x = [
           d[j+1] + 1, # insertion
           e + 1,      # deletion
           d[j] + cost # substitution
          ].min
      d[j] = e
      e = x
    end

    d[m] = x
  end

  return x
end