NAME

    Text::Fingerprint - perform simple text clustering by key collision

VERSION

    version 0.006

SYNOPSIS

        #!/usr/bin/env perl
        use common::sense;
    
        use Text::Fingerprint qw(:all);
    
        my $str = q(
            À noite, vovô Kowalsky vê o ímã cair no pé do pingüim
            queixoso e vovó põe açúcar no chá de tâmaras do jabuti feliz.
        );
    
        say fingerprint($str);
        # a acucar cair cha de do e feliz ima jabuti kowalsky
        # no noite o pe pinguim poe queixoso tamaras ve vovo
    
        say fingerprint_ngram($str);
        # abacadaialamanarasbucachcudedoeaedeieleoetevfeg
        # uhaifiminiritixizjakokylilsmamqngnoocoeoiojokop
        # osovowpepipoqurarnsdsksotatetiucueuiutvevowaxoyv
    
        say fingerprint_ngram($str, 1);
        # abcdefghijklmnopqrstuvwxyz

DESCRIPTION

    Text clustering functions borrowed from the Google Refine
    <http://code.google.com/p/google-refine/>. Can be useful for finding
    groups of different values that might be alternative representations of
    the same thing. For example, the two strings "New York" and "new york"
    are very likely to refer to the same concept and just have
    capitalization differences. Likewise, "Gödel" and "Godel" probably
    refer to the same person.

FUNCTIONS

 fingerprint($string)

    The process that generates the key from a $string value is the
    following (note that the order of these operations is significant):

      * normalize extended western characters to their ASCII representation
      (for example "gödel" → "godel")

      * change all characters to their lowercase representation

      * remove leading and trailing whitespace

      * split the string into punctuation, whitespace and control
      characters-separated tokens (using /[\W_]/ regexp)

      * sort the tokens and remove duplicates

      * join the tokens back together

 fingerprint_ngram($string, $n)

    The n-gram <http://en.wikipedia.org/wiki/N-gram> fingerprint method is
    similar to the fingerprint method described above but instead of using
    whitespace separated tokens, it uses n-grams, where the $n (or the size
    in chars of the token) can be specified by the user (default: 2).
    Algorithm steps:

      * normalize extended western characters to their ASCII representation

      * change all characters to their lowercase representation

      * remove all punctuation, whitespace, and control characters (using
      /[\W_]/ regexp)

      * obtain all the string n-grams

      * sort the n-grams and remove duplicates

      * join the sorted n-grams back together

CAVEAT

    Fingerprint functions are not exactly the same as those found in Google
    Refine! They were slightly changed to take advantage of the superb Perl
    handling of Unicode characters.

SEE ALSO

      * Text::Unidecode

      * Methods and theory behind the clustering functionality in Google
      Refine.
      <http://code.google.com/p/google-refine/wiki/ClusteringInDepth>

AUTHOR

    Stanislaw Pusep <stas@sysd.org>

COPYRIGHT AND LICENSE

    This software is copyright (c) 2014 by Stanislaw Pusep.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.

