Class: FuzzyStrings

Inherits:
Object
  • Object
show all
Defined in:
lib/fuzzy_strings.rb

Overview

Match words based on the operations needed to get 2 similar words bt insertion, deletion, substitution or transposition operations.

cot => coat (a must be inserted to get the same word) coat => cot (a must be deleted to get the same word) cost => coat (a must be substituted with s to get the same word) foo => floor (l and r must be inserted) floor => foo (l and r must be deleted) cost => cots (t and s must substituted (cost=2) or transpositioned (cost=1))

the cost is the amount of operations needed to make 2 words the same

Usage

fs = FuzzyStrings.new("pattern")
match = fs.compare("pattren")
puts match.match?
# true
puts match.score
# 2
puts match

Unicode?

It is assumed that all strings are utf-8

Defined Under Namespace

Classes: Match

Instance Method Summary collapse

Constructor Details

#initialize(string1) ⇒ FuzzyStrings

Returns a new instance of FuzzyStrings.



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# File 'lib/fuzzy_strings.rb', line 26

def initialize(string1)
  @string1 = string1.to_s rescue ""
end

Instance Method Details

#compare(string2, no_transpositions = false) ⇒ Object

compare a given string to the base pattern, the compared strings is operated upon (soo cot as the pattern and coat in compare leads to deletion)

returns a FuzzyStrings::Match object



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# File 'lib/fuzzy_strings.rb', line 35

def compare(string2, no_transpositions = false)
  @string2 = string2.to_s rescue ""
  @match   = Match.new

  return @match if @string1 == @string2

  rule = 'U*'

  sequence1 = @string1.unpack rule
  sequence2 = @string2.unpack rule

  if (sequence1 + sequence2).include?(0)
    raise ArgumentError.new(
      "Strings cannot contain NULL-bytes due to internal semantics"
    )
  end

  @short, @long = if sequence1.length < sequence2.length
    [sequence1, sequence2]
  else
    [sequence2, sequence1]
  end

  find_insertions
  find_substitutions
  find_transpositions unless no_transpositions == true

  return @match
end