Module: Hotwater

Defined in:
lib/hotwater.rb,
lib/hotwater/version.rb,
lib/hotwater/jaro_ffi.rb,
lib/hotwater/ngram_ffi.rb,
lib/hotwater/levenshtein_ffi.rb,
lib/hotwater/damerau_levenshtein_ffi.rb

Defined Under Namespace

Modules: C

Constant Summary collapse

VERSION = 
"0.1.2"

Class Method Summary collapse

Class Method Details

.damerau_levenshtein_distance(s1, s2) ⇒ Integer

compute Damerau Levenshtein edit distance between 2 strings

Parameters:

  • s1 (String) —

    first string

  • s2 (String) —

    seconds string

Returns:

  • (Integer) —

    edit distance



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# File 'lib/hotwater/damerau_levenshtein_ffi.rb', line 14

def damerau_levenshtein_distance(s1, s2)
  result = C::damerau_levenshtein_distance(s1, s2)
  raise("memory allocation error") if result == -1
  result
end

.jaro_distance(s1, s2) ⇒ Float

compute Jaro edit distance between 2 strings

Parameters:

  • s1 (String) —

    first string

  • s2 (String) —

    seconds string

Returns:

  • (Float) —

    edit distance between 0.0 and 1.0



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# File 'lib/hotwater/jaro_ffi.rb', line 17

def jaro_distance(s1, s2)
  result = C::jaro_distance(s1, s2)
  raise("memory allocation error") if result < 0.0
  result
end

.jaro_winkler_distance(s1, s2, long_tolerance = false) ⇒ Float

compute Jaro-Winkler edit distance between 2 strings

setting ‘long_tolerance = true` increases the probability of a match when the number of matched characters is large. This option allows for a little more tolerance when the strings are large. It is not an appropriate test when comparing fixed length fields such as phone and social security numbers.

Parameters:

  • s1 (String) —

    first string

  • s2 (String) —

    seconds string

  • long_tolerance (Boolean) (defaults to: false) —

    add more tolerance when the strings are large. Default ‘false`

Returns:

  • (Float) —

    edit distance between 0.0 and 1.0



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# File 'lib/hotwater/jaro_ffi.rb', line 34

def jaro_winkler_distance(s1, s2, long_tolerance = false)
  result = C::jaro_winkler_distance(s1, s2, long_tolerance)
  raise("memory allocation error") if result < 0.0
  result
end

.levenshtein_distance(s1, s2) ⇒ Integer

compute Levenshtein edit distance between 2 strings

Parameters:

  • s1 (String) —

    first string

  • s2 (String) —

    seconds string

Returns:

  • (Integer) —

    edit distance



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# File 'lib/hotwater/levenshtein_ffi.rb', line 14

def levenshtein_distance(s1, s2)
  result = C::levenshtein_distance(s1, s2)
  raise("memory allocation error") if result == -1
  result
end

.ngram_distance(s1, s2, n = 2) ⇒ Float

compute N-Gram distance between 2 strings

Parameters:

  • s1 (String) —

    first string

  • s2 (String) —

    seconds string

  • n (Integer) (defaults to: 2) —

    number of characters per gram, default is 2

Returns:

  • (Float) —

    edit distance between 0.0 and 1.0



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# File 'lib/hotwater/ngram_ffi.rb', line 15

def ngram_distance(s1, s2, n = 2)
  result = C::ngram_distance(s1, s2, n)
  raise("memory allocation error") if result == -1
  result
end

.normalized_damerau_levenshtein_distance(s1, s2) ⇒ Float

compute normalized Damerau Levenshtein edit distance between 2 strings normalization weight the edit distance using the string lengths where an edit on a small string has more impact than on a longer string

Parameters:

  • s1 (String) —

    first string

  • s2 (String) —

    seconds string

Returns:

  • (Float) —

    edit distance between 0.0 and 1.0



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# File 'lib/hotwater/damerau_levenshtein_ffi.rb', line 26

def normalized_damerau_levenshtein_distance(s1, s2)
  result = C::damerau_levenshtein_distance(s1, s2)
  raise("memory allocation error") if result == -1
  return 0.0 if result == 0.0
  max = [s1.size, s2.size].max
  (max - result.to_f) / max
end

.normalized_levenshtein_distance(s1, s2) ⇒ Float

compute normalized Levenshtein edit distance between 2 strings normalization weight the edit distance using the string lengths where an edit on a small string has more impact than on a longer string

Parameters:

  • s1 (String) —

    first string

  • s2 (String) —

    seconds string

Returns:

  • (Float) —

    edit distance between 0.0 and 1.0



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# File 'lib/hotwater/levenshtein_ffi.rb', line 26

def normalized_levenshtein_distance(s1, s2)
  result = C::levenshtein_distance(s1, s2)
  raise("memory allocation error") if result == -1
  return 0.0 if result == 0.0
  max = [s1.size, s2.size].max
  (max - result.to_f) / max
end