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++ Userâs
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.
- double_metaphone(+In, -MetaPhone)
- Same as double_metaphone/3, but only returning the primary metaphone.
- double_metaphone(+In, -MetaPhone, -AltMetaphone)
- Create metaphone and alternative metaphone from In. The primary metaphone is based on english, while the secondary deals with common alternative pronounciation in other languages. In is either and atom, string object, code- or character list. The metaphones are always returned as atoms.
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 <firstname.lastname@example.org>. All rights reserved.
This code is based heavily on the C++ implementation by Lawrence Philips and incorporates several bug fixes courtesy of Kevin Atkinson <email@example.com>.
This module is free software; you may redistribute it and/or modify it under the same terms as Perl itself.
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
- porter_stem(+In, -Stem)
- Determine the stem of In. In must represent ISO Latin-1 text. The porter_stem/2 predicate first maps In to lower case, then removes all accents as in unaccent_atom/2 and finally applies the Porter stem algorithm.
- unaccent_atom(+In, -ASCII)
- If In is general ISO Latin-1 text with accents, ASCII is unified with a plain ASCII version of the string. Note that the current version only deals with ISO Latin-1 atoms.
- tokenize_atom(+In, -TokenList)
- Break the text In into words, numbers and punctuation
characters. Tokens are created to the following rules:
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.
- atom_to_stem_list(+In, -ListOfStems)
- Combines the three above routines, returning a list holding an atom with the stem of each word encountered and numbers for encountered numbers.
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:
- snowball/3 stems a word with a given algorithm
- snowball_current_algorithm/1 enumerates the provided algorithms.
Here is an example:
?- snowball(english, walking, S). S = walk.
- [det]snowball(+Algorithm, +Input, -Stem)
- Apply the Snowball Algorithm on Input and unify
the result (an atom) with Stem.
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.
- True if Algorithm is the official name of an algorithm
suported by snowball/3. The
semidetif Algorithm is given.
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.
- [det]isub(+Text1:atomic, +Text2:atomic, +Normalize:bool, -Similarity:float)
- Similarity is a measure for the distance between Text1
?- 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
Installation on Unix system uses the commonly found configure,
make and make install sequence. SWI-Prolog should be
installed before building this package. If SWI-Prolog is not installed
as pl, the environment variable
PL must be set to
the name of the SWI-Prolog executable. Installation is now accomplished
% ./configure % make % make install
This installs the foreign libraries in
and the Prolog library files in
$PLBASE refers to the SWI-Prolog `home-directory'.