Text::Brew(3pm)

1Text::Brew(3)         User Contributed Perl Documentation        Text::Brew(3)
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NAME

6       Text::Brew - An implementation of the Brew edit distance
7

SYNOPSIS

9        use Text::Brew qw(distance);
10
11        my ($distance,$arrayref_edits)=distance("four","foo");
12        my $sequence=join",",@$arrayref_edits;
13        print "The Brew distance for (four,foo) is $distance\n";
14        print "obtained with the edits: $sequence\n\n";
15

DESCRIPTION

17       This module implements the Brew edit distance that is very close to the
18       dynamic programming technique used for the Wagner-Fischer (and so for
19       the Levenshtein) edit distance. Please look at the module references
20       below.  For more information about the Brew edit distance see:
21       <http://ling.ohio-state.edu/~cbrew/795M/string-distance.html>
22
23       The difference here is that you have separated costs for the DELetion
24       and INSertion operations (but with the default to 1 for both, you
25       obtain the Levenshtein edit distance). But the most interesting feature
26       is that you can obtain the description of the edits needed to transform
27       the first string into the second one (not vice versa: here DELetions
28       are separated from INSertions).  The difference from the original
29       algorithm by Chris Brew is that I have added the SUBST operation,
30       making it different from MATCH operation.
31
32       The symbols used here are:
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34        INITIAL that is the INITIAL operation (i.e. NO operation)
35        MATCH   that is the MATCH operation (0 is the default cost)
36        SUBST   that is the SUBSTitution operation (1 is the default cost)
37        DEL     that is the DELetion operation (1 is the default cost)
38        INS     that is the INSertion operation (1 is the default cost)
39
40       and you can change the default costs (see below).
41
42       You can make INS and DEL the same operation in a simple way:
43
44        1) give both the same cost
45        2) change the output string DEL to INS/DEL (o whatever)
46        3) change the output string INS to INS/DEL (o whatever)
47
48   USAGE
49        use strict;
50        use Text::Brew qw(distance);
51
52        my ($distance,$arrayref_edits)=distance("four","foo");
53        my $sequence=join",",@$arrayref_edits;
54        print "The Brew distance for (four,foo) is $distance\n";
55        print "obtained with the edits: $sequence\n\n";
56
57        my $string1="foo";
58        my @strings=("four","foo","bar");
59        my (@dist,@edits);
60        foreach my $string2 (@strings) {
61               my ($dist,$edits)=distance($string1,$string2);
62               push @dist,$dist;
63               push @edits,(join ",",@$edits);
64        }
65        foreach my $i (0 .. $#strings) {
66
67               print "The Brew distance for ($string1,$strings[$i]) is $dist[$i]\n";
68               print "obtained with the edits: $edits[$i]\n\n";
69        }
70
71   OPTIONAL PARAMETERS
72        distance($string1,$string2,{-cost=>[0,2,1,1],-output=>'edits'});
73
74        -output
75        accepted values are:
76               distance        means that the distance returns
77                               only the numeric distance
78
79               both    the distance returns both the
80                       numeric distance and the array of the edits
81
82               edits   means that the distance returns only the
83                       array of the edits
84
85        Default output is 'both'.
86
87        -cost
88        accepted value is an array with 4 elements:
89        1st is the cost for the MATCH
90        2nd is the cost for the INS (INSertion)
91        3rd is the cost for the DEL (DELetion)
92        4th is the cost for the SUBST (SUBSTitution)
93
94        Default array is [0,1,1,1] .
95
96        Examples are:
97
98        my $distance=distance("four","foo",{-output=>'distance'});
99        print "The Brew distance for (four,foo) is $distance\n\n";
100
101
102        my $arrayref_edits=distance("four","foo",{-output=>'edits'});
103        my $sequence=join",",@$arrayref_edits;
104        print "The Brew sequence for (four,foo) is $sequence\n\n";
105
106
107        my ($distance,$arrayref_edits)=distance("four","foo",{-cost=>[0,2,1,1]});
108        my $sequence=join",",@$arrayref_edits;
109        print "The Brew distance for (four,foo) is $distance\n";
110        print "obtained with the edits: $sequence\n\n";
111
112        ($distance,$arrayref_edits)=distance("foo","four",{-cost=>[0,2,1,1]});
113        $sequence=join",",@$arrayref_edits;
114        print "The Brew distance for (foo,four) is $distance\n";
115        print "obtained with the edits: $sequence\n\n";
116

CREDITS

118       All the credits goes to Chris Brew the author of the algorithm.
119

THANKS

121       Many thanks to Stefano L. Rodighiero <larsen at perlmonk.org> for the
122       suggestions.
123

AUTHOR

125       Copyright 2003 Dree Mistrut <dree@friuli.to>
126
127       This package is free software and is provided "as is" without express
128       or implied warranty. You can redistribute it and/or modify it under the
129       same terms as Perl itself.
130

NAME

SYNOPSIS

DESCRIPTION

CREDITS

THANKS

AUTHOR

SEE ALSO