


Text::Soundex(3p)Perl Programmers Reference GuidText::Soundex(3p)


NAME
       Text::Soundex - Implementation of the Soundex Algorithm as
       Described by Knuth

SYNOPSIS
         use Text::Soundex;

         $code = soundex $string;            # get soundex code for a string
         @codes = soundex @list;             # get list of codes for list of strings

         # set value to be returned for strings without soundex code

         $soundex_nocode = 'Z000';


DESCRIPTION
       This module implements the soundex algorithm as described
       by Donald Knuth in Volume 3 of The Art of Computer
       Programming.  The algorithm is intended to hash words (in
       particular surnames) into a small space using a simple
       model which approximates the sound of the word when spoken
       by an English speaker.  Each word is reduced to a four
       character string, the first character being an upper case
       letter and the remaining three being digits.

       If there is no soundex code representation for a string
       then the value of $soundex_nocode is returned.  This is
       initially set to undef, but many people seem to prefer an
       unlikely value like Z000 (how unlikely this is depends on
       the data set being dealt with.)  Any value can be assigned
       to $soundex_nocode.

       In scalar context soundex returns the soundex code of its
       first argument, and in array context a list is returned in
       which each element is the soundex code for the
       corresponding argument passed to soundex e.g.

         @codes = soundex qw(Mike Stok);

       leaves @codes containing ('M200', 'S320').

EXAMPLES
       Knuth's examples of various names and the soundex codes
       they map to are listed below:

         Euler, Ellery -> E460
         Gauss, Ghosh -> G200
         Hilbert, Heilbronn -> H416
         Knuth, Kant -> K530
         Lloyd, Ladd -> L300
         Lukasiewicz, Lissajous -> L222

       so:




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Text::Soundex(3p)Perl Programmers Reference GuidText::Soundex(3p)


         $code = soundex 'Knuth';              # $code contains 'K530'
         @list = soundex qw(Lloyd Gauss);      # @list contains 'L300', 'G200'


LIMITATIONS
       As the soundex algorithm was originally used a long time
       ago in the US it considers only the English alphabet and
       pronunciation.

       As it is mapping a large space (arbitrary length strings)
       onto a small space (single letter plus 3 digits) no
       inference can be made about the similarity of two strings
       which end up with the same soundex code.  For example,
       both Hilbert and Heilbronn end up with a soundex code of
       H416.

AUTHOR
       This code was implemented by Mike Stok (stok@cybercom.net)
       from the description given by Knuth.  Ian Phillips
       (ian@pipex.net) and Rich Pinder (rpinder@hsc.usc.edu)
       supplied ideas and spotted mistakes.




































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