


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 Pro-
       gramming.  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 list context a list is returned
       in which each element is the soundex code for the corre-
       sponding 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:




2001-05-24                 perl v5.6.1                          1





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 infer-
       ence 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@cyber-
       com.net") from the description given by Knuth.  Ian
       Phillips ("ian@pipex.net") and Rich Pinder ("rpin-
       der@hsc.usc.edu") supplied ideas and spotted mistakes.




































2001-05-24                 perl v5.6.1                          2


