1Text::Soundex(3pm)     Perl Programmers Reference Guide     Text::Soundex(3pm)
2
3
4

NAME

6       Text::Soundex - Implementation of the Soundex Algorithm as Described by
7       Knuth
8

SYNOPSIS

10         use Text::Soundex;
11
12         $code = soundex $string;            # get soundex code for a string
13         @codes = soundex @list;             # get list of codes for list of strings
14
15         # set value to be returned for strings without soundex code
16
17         $soundex_nocode = 'Z000';
18

DESCRIPTION

20       This module implements the soundex algorithm as described by Donald
21       Knuth in Volume 3 of The Art of Computer Programming.  The algorithm is
22       intended to hash words (in particular surnames) into a small space
23       using a simple model which approximates the sound of the word when spo‐
24       ken by an English speaker.  Each word is reduced to a four character
25       string, the first character being an upper case letter and the remain‐
26       ing three being digits.
27
28       If there is no soundex code representation for a string then the value
29       of $soundex_nocode is returned.  This is initially set to "undef", but
30       many people seem to prefer an unlikely value like "Z000" (how unlikely
31       this is depends on the data set being dealt with.)  Any value can be
32       assigned to $soundex_nocode.
33
34       In scalar context "soundex" returns the soundex code of its first argu‐
35       ment, and in list context a list is returned in which each element is
36       the soundex code for the corresponding argument passed to "soundex"
37       e.g.
38
39         @codes = soundex qw(Mike Stok);
40
41       leaves @codes containing "('M200', 'S320')".
42

EXAMPLES

44       Knuth's examples of various names and the soundex codes they map to are
45       listed below:
46
47         Euler, Ellery -> E460
48         Gauss, Ghosh -> G200
49         Hilbert, Heilbronn -> H416
50         Knuth, Kant -> K530
51         Lloyd, Ladd -> L300
52         Lukasiewicz, Lissajous -> L222
53
54       so:
55
56         $code = soundex 'Knuth';              # $code contains 'K530'
57         @list = soundex qw(Lloyd Gauss);      # @list contains 'L300', 'G200'
58

LIMITATIONS

60       As the soundex algorithm was originally used a long time ago in the US
61       it considers only the English alphabet and pronunciation.
62
63       As it is mapping a large space (arbitrary length strings) onto a small
64       space (single letter plus 3 digits) no inference can be made about the
65       similarity of two strings which end up with the same soundex code.  For
66       example, both "Hilbert" and "Heilbronn" end up with a soundex code of
67       "H416".
68

AUTHOR

70       This code was implemented by Mike Stok ("stok@cybercom.net") from the
71       description given by Knuth.  Ian Phillipps ("ian@pipex.net") and Rich
72       Pinder ("rpinder@hsc.usc.edu") supplied ideas and spotted mistakes.
73
74
75
76perl v5.8.8                       2001-09-21                Text::Soundex(3pm)
Impressum