The library library(double_metaphone) implements the Double
Metaphone algorithm developed by Lawrence Philips and described in
``The Double-Metaphone Search Algorithm'' by L Philips, C/C++ User’s
Journal, 2000. Double Metaphone creates a key from a word that
represents its phonetic properties. Two words with the same Double
Metaphone are supposed to sound similar. The Double Metaphone algorithm
is an improved version of the Soundex algorithm.
The Double Metaphone algorithm is copied from the Perl library that holds the following copyright notice. To the best of our knowledge the Perl license is compatible to the SWI-Prolog license schema and therefore including this module poses no additional license conditions.
Copyright 2000, Maurice Aubrey <maurice@hevanet.com>. All rights reserved.This code is based heavily on the C++ implementation by Lawrence Philips and incorporates several bug fixes courtesy of Kevin Atkinson <kevina@users.sourceforge.net>.
This module is free software; you may redistribute it and/or modify it under the same terms as Perl itself.
The library(porter_stem) library implements the stemming
algorithm described by Porter in Porter, 1980, ``An algorithm for suffix
stripping'', Program, Vol. 14, no. 3, pp 130-137. The library comes with
some additional predicates that are commonly used in the context of
stemming.
[-+][0-9]+(\.[0-9]+)?([eE][-+][0-9]+)? | number |
[:alpha:][:alnum:]+ | word |
[:space:]+ | skipped |
| anything else | single-character |
Character classification is based on the C-library iswalnum() etc. functions.
It is likely that future versions of this library will provide tokenize_atom/3 with additional options to modify space handling as well as the definition of words.
The code is based on the original Public Domain implementation by Martin Porter as can be found at http://www.tartarus.org/martin/PorterStemmer/. The code has been modified by Jan Wielemaker. He removed all global variables to make the code thread-safe, added the unaccent and tokenize code and created the SWI-Prolog binding.
This module encapsulates "The C version of the libstemmer library" from the Snowball project. This library provides stemmers in a variety of languages. The interface to this library is very simple:
Here is an example:
?- snowball(english, walking, S). S = walk.
The implementation maintains a cache of stemmers for each thread that accesses snowball/3, providing high-perfomance and thread-safety without locking.
| Algorithm | is the (english) name for desired algorithm or an 2 or 3 letter ISO 639 language code. |
| Input | is the word to be stemmed. It is either an atom, string or list of chars/codes. The library accepts Unicode characters. Input must be lowercase. See downcase_atom/2. |
semidet if Algorithm is given.
The library(isub) implements a similarity measure
between strings, i.e., something similar to the Levenshtein distance.
This method is based on the length of common substrings.
?- isub('E56.Language', 'languange', true, D).
D = 0.711348.
If Normalize is true, isub/4
applies string normalization as implemented by the original authors: Text1
and Text2 are mapped to lowercase and the characters "._ "
are removed. Lowercase mapping is done with the C-library function
towlower(). In general, the required normalization is domain dependent
and is better left to the caller. See e.g., unaccent_atom/2.
| Similarity | is a float in the range [0.0..1.0], where 1.0 means most similar |