NAME

NAME
"Text::Categorize::Textrank" - Method to rank potential keywords of
text.

SYNOPSIS
use strict;
use warnings;
use Text::Categorize::Textrank;
use Data::Dump qw(dump);
my $listOfTokens = [ [qw(This is the first sentence)], [qw(Here is the second sentence)] ];
my $hashOfTextrankValues = getTextrankOfListOfTokens(listOfTokens => $listOfTokens);
dump $hashOfTextrankValues;

DESCRIPTION
"Text::Categorize::Textrank" provides a routine for ranking the words in
text as potential keywords. It implements a version of the textrank
algorithm from the report *TextRank: Bringing Order into Texts* by R.
Mihalcea and P. Tarau.

ROUTINES
"getTextrankOfListOfTokens"
The routine "getTextrankOfListOfTokens" returns a hash reference
containing the textrank value for all the tokens in the lists provided;
the textrank values sum to one. The textrank of a token is its pagerank
in the graph obtained by joining neighboring tokens with an edge, called
the token graph.

Usually, "listOfTokens" should *not* be applied to all the words of the
text. The complete textrank algorithm first filters the words in the
text to only the nouns and adjectives. See
Text::Categorize::Textrank::En to compute the textrank of English text.

"listOfTokens"
listOfTokens => [[...], [...], ...[...]]

"listOfTokens" is an array reference containing the list of tokens
that are to be ranked using textrank. Each list is also an array
reference of tokens that should correspond to the list of tokens in
a sentence. For example, "[[qw(This is the first sentence)],
[qw(Here is the second sentence)]]".

"edgeCreationSpan"
edgeCreationSpan => 1

For each token in the "listOfTokens", "edgeCreationSpan" is the
number of successive tokens used to make an edge in the token graph.
For example, if "edgeCreationSpan" is two, then given the token
sequence "apple orange pear" the edges "[apple, orange]" and
"[apple, pear]" will be added to the token graph for the token
"apple". The default is one.

Note that loop edges are ignored. For example, if "edgeCreationSpan"
is two, then given the token sequence "daba daba doo" the edge
"[daba, daba]" is disguarded but the edge "[daba, doo]" is added to
the token graph.

"directedGraph"
directedGraph => 0

If "directedGraph" is true, the textranks are computed from the
directed token graph, if false, they are computed from the
undirected version of the graph. The default is false.

"dampeningFactor"
dampeningFactor => 0.85

When computing the textranks of the token graph, the dampening
factor specified by "dampeningFactor" will be used; it should range
from zero to one. The default is 0.85.

"addEdgesSpanningLists"
addEdgesSpanningLists => 1

If "addEdgesSpanningLists" is true, then when building the token
graph, links between the tokens at the end of a list and the
beginning of the next list will be made. For example, for the lists
"[[qw(This is the first list)], [qw(Here is the second list)]]" the
edge "[list, Here]" will be added to the token graph. The default is
true.

"tokenWeights"
tokenWeights => {}

"tokenWeights" is an optional hash reference that can provide a
weight for a subset of the tokens provided by "listOfTokens". If
"tokenWeights" is not defined for any token in "listOfTokens", then
each token has a weight of one. If "tokenWeights" is defined for at
least one node in the graph, then the default weight of any
undefined token is zero.

INSTALLATION
To install the module run the following commands:

perl Makefile.PL
make
make test
make install

If you are on a windows box you should use 'nmake' rather than 'make'.

BUGS
Please email bugs reports or feature requests to
"[email protected]", or through the web interface
at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Text-Categorize-Textrank
>. The author will be notified and you can be automatically notified of
progress on the bug fix or feature request.

AUTHOR
Jeff Kubina<[email protected]>

COPYRIGHT
Copyright (c) 2009 Jeff Kubina. All rights reserved. This program is
free software; you can redistribute it and/or modify it under the same
terms as Perl itself.

The full text of the license can be found in the LICENSE file included
with this module.

KEYWORDS
categorize, keywords, keyphrases, nlp, pagerank, textrank

SEE ALSO
Graph, Graph::Centrality::Pagerank, Log::Log4perl,
Text::Categorize::Textrank::En