Class: Komainu::CalculatesLevenshteinDistance

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

Instance Method Summary collapse

Constructor Details

#initialize(words) ⇒ CalculatesLevenshteinDistance

Returns a new instance of CalculatesLevenshteinDistance.



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# File 'lib/komainu/calculates_levenshtein_distance.rb', line 5

def initialize(words)
  @trie = TrieNode.new
  words.each do |word|
    @trie.insert(word)
  end
end

Instance Method Details

#search(word, maximum_distance) ⇒ Object 



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# File 'lib/komainu/calculates_levenshtein_distance.rb', line 12

def search word, maximum_distance
  current_row = (0..word.length).to_a
  results = {}
  @trie.children.keys.each do |letter|
    search_recursive(@trie.children[letter], letter, word, current_row, results, maximum_distance)
  end
  results
end

#search_recursive(node, letter, word, previous_row, results, maximum_distance) ⇒ Object 



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# File 'lib/komainu/calculates_levenshtein_distance.rb', line 21

def search_recursive node, letter, word, previous_row, results, maximum_distance
  columns = word.length + 1
  current_row = [previous_row.first + 1]

  (1...columns).each do |column|
    insert_cost = current_row[column - 1] + 1
    delete_cost = previous_row[column] + 1

    if word[column - 1] != letter[0]
      replace_cost = previous_row[column - 1] + 1
    else
      replace_cost = previous_row[column - 1]
    end

    current_row << [insert_cost, delete_cost, replace_cost].min
  end

  if current_row.last <= maximum_distance && node.word
    results[node.word] = current_row.last
  end

  if current_row.min <= maximum_distance
    node.children.keys.each do |letter|
      search_recursive(node.children[letter], letter, word, current_row, results, maximum_distance)
    end
  end
end