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Revision: 1.1
Committed: Sat Jun 25 09:55:53 2005 UTC (19 years ago) by root
Branch: MAIN
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# Content
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 require DynaLoader;
21
22 $VERSION = '1.02';
23 @ISA = qw/Exporter DynaLoader/;
24 @EXPORT = qw(similarity);
25 @EXPORT_OK = qw(fstrcmp);
26
27 bootstrap String::Similarity $VERSION;
28
29 =item $factor = similarity $string1, $string2, [$limit]
30
31 The C<similarity>-function calculates the similarity index of
32 its two arguments. A value of C<0> means that the strings are
33 entirely different. A value of C<1> means that the strings are
34 identical. Everything else lies between 0 and 1 and describes the amount
35 of similarity between the strings.
36
37 It roughly works by looking at the smallest number of edits to change one
38 string into the other.
39
40 You can add an optional argument C<$limit> (default 0) that gives the
41 minimum similarity the two strings must satisfy. C<similarity> stops
42 analyzing the string as soon as the result drops below the given limit,
43 in which case the result will be invalid but lower than the given
44 C<$limit>. You can use this to speed up the common case of searching for
45 the most similar string from a set by specifing the maximum similarity
46 found so far.
47
48 =cut
49
50 # out of historical reasons, I prefer "fstrcmp" as the original name.
51 *similarity = *fstrcmp;
52
53 1;
54
55 =back
56
57 =head1 SEE ALSO
58
59 The basic algorithm is described in:
60 "An O(ND) Difference Algorithm and its Variations", Eugene Myers,
61 Algorithmica Vol. 1 No. 2, 1986, pp. 251-266;
62 see especially section 4.2, which describes the variation used below.
63
64 The basic algorithm was independently discovered as described in:
65 "Algorithms for Approximate String Matching", E. Ukkonen,
66 Information and Control Vol. 64, 1985, pp. 100-118.
67
68 =head1 AUTHOR
69
70 Marc Lehmann <schmorp@schmorp.de>
71 http://home.schmorp.de/
72
73 (the underlying fstrcmp function was taken from gnu diffutils and
74 modified by Peter Miller <pmiller@agso.gov.au> and Marc Lehmann
75 <schmorp@schmorp.de>).
76
77
78