32 lines
724 B
Ruby
32 lines
724 B
Ruby
module RailsGuides
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module Levenshtein
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# Based on the pseudocode in http://en.wikipedia.org/wiki/Levenshtein_distance.
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def self.distance(s1, s2)
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s = s1.unpack('U*')
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t = s2.unpack('U*')
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m = s.length
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n = t.length
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# matrix initialization
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d = []
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0.upto(m) { |i| d << [i] }
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0.upto(n) { |j| d[0][j] = j }
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# distance computation
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1.upto(m) do |i|
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1.upto(n) do |j|
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cost = s[i] == t[j] ? 0 : 1
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d[i][j] = [
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d[i-1][j] + 1, # deletion
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d[i][j-1] + 1, # insertion
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d[i-1][j-1] + cost, # substitution
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].min
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end
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end
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# all done
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return d[m][n]
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end
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end
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end
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