# Measure the distance between two strings with Ruby?

Can I measure the distance between two strings with Ruby?

**I.e.:**

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

## Answers

I found this for you:

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

That's awesome output: =)

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

Source: http://rosettacode.org/wiki/Levenshtein_distance#Ruby