45 lines
1.0 KiB
Ruby
45 lines
1.0 KiB
Ruby
# frozen_string_literal: true
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module RailsGuides
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module Levenshtein
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# This code is based directly on the Text gem implementation.
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# Copyright (c) 2006-2013 Paul Battley, Michael Neumann, Tim Fletcher.
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#
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# Returns a value representing the "cost" of transforming str1 into str2
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def self.distance(str1, str2)
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s = str1
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t = str2
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n = s.length
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m = t.length
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return m if 0 == n
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return n if 0 == m
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d = (0..m).to_a
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x = nil
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# avoid duplicating an enumerable object in the loop
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str2_codepoint_enumerable = str2.each_codepoint
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str1.each_codepoint.with_index do |char1, i|
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e = i + 1
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str2_codepoint_enumerable.with_index do |char2, j|
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cost = (char1 == char2) ? 0 : 1
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x = [
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d[j + 1] + 1, # insertion
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e + 1, # deletion
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d[j] + cost # substitution
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].min
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d[j] = e
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e = x
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end
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d[m] = x
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end
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x
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end
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end
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end
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