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

VERSION
    version 0.004

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):

    *   remove leading and trailing whitespace

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

    *   change all characters to their lowercase representation

    *   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:

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

    *   normalize extended western characters to their ASCII representation

    *   change all characters to their lowercase representation

    *   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) 2012 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.