Edit distance calculation [ Ruby ]

edit_distance.rb

module Analyzer
  class EditDistance
    attr_accessor :word1, :word2, :matrix

    def initialize(word1, word2)
      @word1 = word1
      @word2 = word2
      @w1l = @word1.length
      @w2l = @word2.length
      @matrix = Array.new(@w1l+1){Array.new(@word2.length+1){|i| 0}}
    end

    def calculate_matrix
      for j in 0..(@w2l)
        @matrix[0][j] = j
      end
      for i in 0..(@w1l)
        @matrix[i][0] = i
      end
      for i in 1..(@w1l)
        for j in 1..(@w2l)
          @matrix[i][j] = [[@matrix[i][j-1]+1, @matrix[i-1][j]+1].min, @matrix[i-1][j-1] + compare_symbs(@word1[i-1],@word2[j-1]) ].min
        end
      end
      @range = @matrix[@w1l][@w2l]
    end

    def get_range
      @range
    end

    private

    def compare_symbs(a,b)
      a==b ? 0 : 1
    end
  end
end