You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
150 lines
4.3 KiB
150 lines
4.3 KiB
package Text::Soundex;
|
|
require 5.000;
|
|
require Exporter;
|
|
|
|
@ISA = qw(Exporter);
|
|
@EXPORT = qw(&soundex $soundex_nocode);
|
|
|
|
$VERSION = '1.0';
|
|
|
|
# $Id: soundex.pl,v 1.2 1994/03/24 00:30:27 mike Exp $
|
|
#
|
|
# Implementation of soundex algorithm as described by Knuth in volume
|
|
# 3 of The Art of Computer Programming, with ideas stolen from Ian
|
|
# Phillips <[email protected]>.
|
|
#
|
|
# Mike Stok <[email protected]>, 2 March 1994.
|
|
#
|
|
# Knuth's test cases are:
|
|
#
|
|
# Euler, Ellery -> E460
|
|
# Gauss, Ghosh -> G200
|
|
# Hilbert, Heilbronn -> H416
|
|
# Knuth, Kant -> K530
|
|
# Lloyd, Ladd -> L300
|
|
# Lukasiewicz, Lissajous -> L222
|
|
#
|
|
# $Log: soundex.pl,v $
|
|
# Revision 1.2 1994/03/24 00:30:27 mike
|
|
# Subtle bug (any excuse :-) spotted by Rich Pinder <[email protected]>
|
|
# in the way I handles leasing characters which were different but had
|
|
# the same soundex code. This showed up comparing it with Oracle's
|
|
# soundex output.
|
|
#
|
|
# Revision 1.1 1994/03/02 13:01:30 mike
|
|
# Initial revision
|
|
#
|
|
#
|
|
##############################################################################
|
|
|
|
# $soundex_nocode is used to indicate a string doesn't have a soundex
|
|
# code, I like undef other people may want to set it to 'Z000'.
|
|
|
|
$soundex_nocode = undef;
|
|
|
|
sub soundex
|
|
{
|
|
local (@s, $f, $fc, $_) = @_;
|
|
|
|
push @s, '' unless @s; # handle no args as a single empty string
|
|
|
|
foreach (@s)
|
|
{
|
|
$_ = uc $_;
|
|
tr/A-Z//cd;
|
|
|
|
if ($_ eq '')
|
|
{
|
|
$_ = $soundex_nocode;
|
|
}
|
|
else
|
|
{
|
|
($f) = /^(.)/;
|
|
tr/AEHIOUWYBFPVCGJKQSXZDTLMNR/00000000111122222222334556/;
|
|
($fc) = /^(.)/;
|
|
s/^$fc+//;
|
|
tr///cs;
|
|
tr/0//d;
|
|
$_ = $f . $_ . '000';
|
|
s/^(.{4}).*/$1/;
|
|
}
|
|
}
|
|
|
|
wantarray ? @s : shift @s;
|
|
}
|
|
|
|
1;
|
|
|
|
__END__
|
|
|
|
=head1 NAME
|
|
|
|
Text::Soundex - Implementation of the Soundex Algorithm as Described by Knuth
|
|
|
|
=head1 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
|
|
|
|
$soundex_nocode = 'Z000';
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
This module implements the soundex algorithm as described by Donald Knuth
|
|
in Volume 3 of B<The Art of Computer Programming>. The algorithm is
|
|
intended to hash words (in particular surnames) into a small space using a
|
|
simple model which approximates the sound of the word when spoken by an English
|
|
speaker. Each word is reduced to a four character string, the first
|
|
character being an upper case letter and the remaining three being digits.
|
|
|
|
If there is no soundex code representation for a string then the value of
|
|
C<$soundex_nocode> is returned. This is initially set to C<undef>, but
|
|
many people seem to prefer an I<unlikely> value like C<Z000>
|
|
(how unlikely this is depends on the data set being dealt with.) Any value
|
|
can be assigned to C<$soundex_nocode>.
|
|
|
|
In scalar context C<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 corresponding argument passed to C<soundex> e.g.
|
|
|
|
@codes = soundex qw(Mike Stok);
|
|
|
|
leaves C<@codes> containing C<('M200', 'S320')>.
|
|
|
|
=head1 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:
|
|
|
|
$code = soundex 'Knuth'; # $code contains 'K530'
|
|
@list = soundex qw(Lloyd Gauss); # @list contains 'L300', 'G200'
|
|
|
|
=head1 LIMITATIONS
|
|
|
|
As the soundex algorithm was originally used a B<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 C<Hilbert> and C<Heilbronn> end up with a soundex code
|
|
of C<H416>.
|
|
|
|
=head1 AUTHOR
|
|
|
|
This code was implemented by Mike Stok (C<[email protected]>) from the
|
|
description given by Knuth. Ian Phillips (C<[email protected]>) and Rich Pinder
|
|
(C<[email protected]>) supplied ideas and spotted mistakes.
|