使用Ruby测量两个字符串之间的距离？

Question

我可以用Ruby测量两个字符串之间的距离吗？

即:

compare('Test', 'est') # Returns 1
compare('Test', 'Tes') # Returns 1
compare('Test', 'Tast') # Returns 1
compare('Test', 'Taste') # Returns 2
compare('Test', 'tazT') # Returns 5

Answer 1

由于本机C绑定,更容易和更快:

gem install levenshtein-ffi
gem install levenshtein

require 'levenshtein'

Levenshtein.normalized_distance string1, string2, threshold

http://rubygems.org/gems/levenshtein http://rubydoc.info/gems/levenshtein/0.2.2/frames

Answer 2

我找到了这个给你:

def levenshtein_distance(s, t)
  m = s.length
  n = t.length
  return m if n == 0
  return n if m == 0
  d = Array.new(m+1) {Array.new(n+1)}

  (0..m).each {|i| d[i][0] = i}
  (0..n).each {|j| d[0][j] = j}
  (1..n).each do |j|
    (1..m).each do |i|
      d[i][j] = if s[i-1] == t[j-1]  # adjust index into string
                  d[i-1][j-1]       # no operation required
                else
                  [ d[i-1][j]+1,    # deletion
                    d[i][j-1]+1,    # insertion
                    d[i-1][j-1]+1,  # substitution
                  ].min
                end
    end
  end
  d[m][n]
end

[ ['fire','water'], ['amazing','horse'], ["bamerindos", "giromba"] ].each do |s,t|
  puts "levenshtein_distance('#{s}', '#{t}') = #{levenshtein_distance(s, t)}"
end

这是非常棒的输出:=)

levenshtein_distance('fire', 'water') = 4
levenshtein_distance('amazing', 'horse') = 7
levenshtein_distance('bamerindos', 'giromba') = 9

资料来源:http://rosettacode.org/wiki/Levenshtein_distance#Ruby

Answer 3

在Rubygems中有一个实用方法实际上应该是公共的但不是,不管怎么说:

require "rubygems/text"
ld = Class.new.extend(Gem::Text).method(:levenshtein_distance)

p ld.call("asd", "sdf") => 2

Answer 4

更简单的是,我有时会露出红宝石......

# Levenshtein distance, translated from wikipedia pseudocode by ross

def lev s, t
  return t.size if s.empty?
  return s.size if t.empty?
  return [ (lev s.chop, t) + 1,
           (lev s, t.chop) + 1,
           (lev s.chop, t.chop) + (s[-1, 1] == t[-1, 1] ? 0 : 1)
       ].min
end

Answer 5

Ruby 2.3 及更高版本附带did_you_meangem，其中包括DidYouMean::Levenshtein.distance. 适用于大多数情况，默认可用。

DidYouMean::Levenshtein.distance("Test", "est") # => 1

Answer 6

我制作了一个damerau-levenshtein gem，其中算法是用 C 实现的

require "damerau-levenshtein"
dl = DamerauLevenshtein
dl.distance("Something", "Smoething") #returns 1