/* Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@vu.nl WWW: http://www.swi-prolog.org Copyright (c) 2011-2021, VU University Amsterdam SWI-Prolog Soutions b.v. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ :- module(isub, [ isub/4, % +Text1, +Text2, -Distance, +Options '$isub'/5 % +Text1, +Text2, -Distance, +Flags, +Threshold ]). :- autoload(library(option), [option/3]). :- use_foreign_library(foreign(isub)). /** isub: a string similarity measure 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. @author Giorgos Stoilos @see _|A string metric for ontology alignment|_ by Giorgos Stoilos, 2005 - http://www.image.ece.ntua.gr/papers/378.pdf . */ %! isub(+Text1:text, +Text2:text, %! -Similarity:float, +Options:list ) is det. % % Similarity is a measure of the similarity/dissimilarity between % Text1 and Text2. E.g. % % ``` % ?- isub('E56.Language', 'languange', D, [normalize(true)]). % D = 0.4226950354609929. % [-1,1] range % % ?- isub('E56.Language', 'languange', D, [normalize(true),zero_to_one(true)]). % D = 0.7113475177304964. % [0,1] range % % ?- isub('E56.Language', 'languange', D, []). % without normalization % D = 0.19047619047619047. % [-1,1] range % % ?- isub(aa, aa, D, []). % does not work for short substrings % D = -0.8. % % ?- isub(aa, aa, D, [substring_threshold(0)]). % works with short substrings % D = 1.0. % but may give unwanted values % % between e.g. 'store' and 'spore'. % % ?- isub(joe, hoe, D, [substring_threshold(0)]). % D = 0.5315315315315314. % % ?- isub(joe, hoe, D, []). % D = -1.0. % ``` % % This is a new version of isub/4 which replaces the old version while % providing backwards compatibility. This new version allows several % options to tweak the algorithm. % % @arg Text1 and Text2 are either an atom, string or a list of % characters or character codes. % @arg Similarity is a float in the range [-1,1.0], where 1.0 % means _|most similar|_. The range can be set to [0,1] with % the zero_to_one option described below. % @arg Options is a list with elements described below. Please % note that the options are processed at compile time using % goal_expansion to provide much better speed. Supported options % are: % % - normalize(+Boolean) % 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. The default % is to skip normalization (`false`). % % - zero_to_one(+Boolean) % The old isub implementation deviated from the original algorithm % by returning a value in the [0,1] range. This new isub/4 implementation % defaults to the original range of [-1,1], but this option can be set % to `true` to set the output range to [0,1]. % % - substring_threshold(+Nonneg) % The original algorithm was meant to compare terms in semantic web % ontologies, and it had a hard coded parameter that only considered % substring similarities greater than 2 characters. This caused the % similarity between, for example 'aa' and 'aa' to return -0.8 which % is not expected. This option allows the user to set any threshold, % such as 0, so that the similatiry between short substrings can be % properly recognized. The default value is 2 which is what the % original algorithm used. isub(T1, T2, Normalize, Similarity) :- ( Normalize == true -> !, '$isub'(T1,T2,Similarity,0x3,2) ; Normalize == false -> !, '$isub'(T1,T2,Similarity,0x1,2) ). isub(T1, T2, Similarity, Options) :- isub_options(NumOpts,SubstringThreshold, Options), '$isub'(T1,T2,Similarity,NumOpts,SubstringThreshold). isub_options(NumOpts,SubstringThreshold, Options) :- option(normalize(Normalize), Options, false), option(zero_to_one(ZeroToOne), Options, false), option(substring_threshold(SubstringThreshold), Options, 2), normalize_int(Normalize,NInt), zero_one_range_int(ZeroToOne,ZInt), NumOpts is NInt \/ ZInt. normalize_int(true,0x2). normalize_int(false,0x0). zero_one_range_int(true,0x1). zero_one_range_int(false,0x0). user:goal_expansion(isub(T1,T2,Normalize,D), '$isub'(T1,T2,D,NumOpts,SubstringThreshold)) :- ( Normalize == true -> NumOpts = 0x3, SubstringThreshold = 2 ; Normalize == true -> NumOpts = 0x1, SubstringThreshold = 2 ). user:goal_expansion(isub(T1,T2,D,Options), '$isub'(T1,T2,D,NumOpts,SubstringThreshold)) :- isub_options(NumOpts,SubstringThreshold, Options). :- multifile sandbox:safe_primitive/1. sandbox:safe_primitive(isub:isub(_,_,_,_)). sandbox:safe_primitive(isub:'$isub'(_,_,_,_,_)).