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Revision: 1.3
Committed: Fri Nov 16 22:55:05 2012 UTC (11 years, 7 months ago) by root
Branch: MAIN
CVS Tags: HEAD
Changes since 1.2: +1 -1 lines
Log Message:
Fabrizio Regalli

File Contents

# User Rev Content
1 root 1.1 =head1 NAME
2    
3     String::Similarity - calculate the similarity of two strings
4    
5     =head1 SYNOPSIS
6    
7     use String::Similarity;
8    
9     $similarity = similarity $string1, $string2;
10     $similarity = similarity $string1, $string2, $limit;
11    
12     =head1 DESCRIPTION
13    
14     =over 4
15    
16     =cut
17    
18     package String::Similarity;
19    
20 root 1.2 use Exporter;
21     use DynaLoader;
22 root 1.1
23 root 1.2 $VERSION = '1.04';
24 root 1.1 @ISA = qw/Exporter DynaLoader/;
25     @EXPORT = qw(similarity);
26     @EXPORT_OK = qw(fstrcmp);
27    
28     bootstrap String::Similarity $VERSION;
29    
30     =item $factor = similarity $string1, $string2, [$limit]
31    
32     The C<similarity>-function calculates the similarity index of
33     its two arguments. A value of C<0> means that the strings are
34     entirely different. A value of C<1> means that the strings are
35     identical. Everything else lies between 0 and 1 and describes the amount
36     of similarity between the strings.
37    
38     It roughly works by looking at the smallest number of edits to change one
39     string into the other.
40    
41     You can add an optional argument C<$limit> (default 0) that gives the
42     minimum similarity the two strings must satisfy. C<similarity> stops
43     analyzing the string as soon as the result drops below the given limit,
44     in which case the result will be invalid but lower than the given
45     C<$limit>. You can use this to speed up the common case of searching for
46 root 1.3 the most similar string from a set by specifying the maximum similarity
47 root 1.1 found so far.
48    
49     =cut
50    
51     # out of historical reasons, I prefer "fstrcmp" as the original name.
52     *similarity = *fstrcmp;
53    
54     1;
55    
56     =back
57    
58     =head1 SEE ALSO
59    
60     The basic algorithm is described in:
61     "An O(ND) Difference Algorithm and its Variations", Eugene Myers,
62     Algorithmica Vol. 1 No. 2, 1986, pp. 251-266;
63     see especially section 4.2, which describes the variation used below.
64    
65     The basic algorithm was independently discovered as described in:
66     "Algorithms for Approximate String Matching", E. Ukkonen,
67     Information and Control Vol. 64, 1985, pp. 100-118.
68    
69     =head1 AUTHOR
70    
71     Marc Lehmann <schmorp@schmorp.de>
72     http://home.schmorp.de/
73    
74     (the underlying fstrcmp function was taken from gnu diffutils and
75     modified by Peter Miller <pmiller@agso.gov.au> and Marc Lehmann
76     <schmorp@schmorp.de>).
77    
78    
79