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145 lines
4.0 KiB
Plaintext
145 lines
4.0 KiB
Plaintext
/*
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* fuzzystrmatch.c
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*
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* Functions for "fuzzy" comparison of strings
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*
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* Joe Conway <mail@joeconway.com>
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*
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* Copyright (c) 2001-2007, PostgreSQL Global Development Group
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* ALL RIGHTS RESERVED;
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*
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* levenshtein()
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* -------------
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* Written based on a description of the algorithm by Michael Gilleland
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* found at http://www.merriampark.com/ld.htm
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* Also looked at levenshtein.c in the PHP 4.0.6 distribution for
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* inspiration.
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*
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* metaphone()
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* -----------
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* Modified for PostgreSQL by Joe Conway.
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* Based on CPAN's "Text-Metaphone-1.96" by Michael G Schwern <schwern@pobox.com>
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* Code slightly modified for use as PostgreSQL function (palloc, elog, etc).
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* Metaphone was originally created by Lawrence Philips and presented in article
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* in "Computer Language" December 1990 issue.
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*
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* dmetaphone() and dmetaphone_alt()
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* ---------------------------------
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* A port of the DoubleMetaphone perl module by Andrew Dunstan. See dmetaphone.c
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* for more detail.
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*
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* soundex()
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* -----------
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* Folded existing soundex contrib into this one. Renamed text_soundex() (C function)
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* to soundex() for consistency.
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*
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* difference()
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* ------------
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* Return the difference between two strings' soundex values. Kris Jurka
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*
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* Permission to use, copy, modify, and distribute this software and its
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* documentation for any purpose, without fee, and without a written agreement
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* is hereby granted, provided that the above copyright notice and this
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* paragraph and the following two paragraphs appear in all copies.
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*
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* IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
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* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
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* DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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*/
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Version 0.3 (30 June, 2004):
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Release Notes:
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Version 0.3
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- added double metaphone code from Andrew Dunstan
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- change metaphone so that an empty input string causes an empty
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output string to be returned, instead of throwing an ERROR
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- fixed examples in README.soundex
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Version 0.2
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- folded soundex contrib into this one
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Version 0.1
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- initial release
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Installation:
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Place these files in a directory called 'fuzzystrmatch' under 'contrib' in the PostgreSQL source tree. Then run:
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make
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make install
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You can use fuzzystrmatch.sql to create the functions in your database of choice, e.g.
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psql -U postgres template1 < fuzzystrmatch.sql
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installs following functions into database template1:
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levenshtein() - calculates the levenshtein distance between two strings
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metaphone() - calculates the metaphone code of an input string
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Documentation
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==================================================================
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Name
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levenshtein -- calculates the levenshtein distance between two strings
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Synopsis
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levenshtein(text source, text target)
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Inputs
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source
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any text string, 255 characters max, NOT NULL
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target
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any text string, 255 characters max, NOT NULL
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Outputs
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Returns int
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Example usage
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select levenshtein('GUMBO','GAMBOL');
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==================================================================
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Name
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metaphone -- calculates the metaphone code of an input string
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Synopsis
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metaphone(text source, int max_output_length)
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Inputs
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source
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any text string, 255 characters max, NOT NULL
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max_output_length
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maximum length of the output metaphone code; if longer, the output
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is truncated to this length
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Outputs
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Returns text
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Example usage
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select metaphone('GUMBO',4);
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==================================================================
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-- Joe Conway
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