計算兩個字符串之間的Levenshtein距離

Levenshtein距離 ruby

class String  
  def levenshtein(other, ins=2, del=2, sub=1)  
    return nil if self.nil?  
    return nil if other.nil?  
    dm = []       
    dm[0] = (0..self.length).collect { |i| i * ins }  
    fill = [0] * (self.length - 1)  
    for i in 1..other.length  
      dm[i] = [i * del, fill.flatten]  
    end  
    for i in 1..other.length  
      for j in 1..self.length  
        dm[i][j] = [  
          dm[i-1][j-1] +  
            (self[j-1] == other[i-1] ? 0 : sub),  
          dm[i][j-1] + ins,  
          dm[i-1][j] + del  
        ].min  
      end  
    end  
    dm[other.length][self.length]  
  end
end  
s1 = "ACUGAUGUGA"  
s2 = "AUGGAA"  
d1 = s1.levenshtein(s2)    # 9  
s3 = "pennsylvania"  
s4 = "pencilvaneya"  
d2 = s3.levenshtein(s4)    # 7  
s5 = "abcd"
s6 = "abcd"
d3 = s5.levenshtein(s6)    # 0

定義similar?code

def similar?(other,thresh=2)
    if self.levenshtein(other) < thresh
      true
    else
      false
    end
  end
"polarty".similar?("hilarity")