NAME

Text::Corpus::Summaries::Wikipedia - Creates corpora for summarization testing.

SYNOPSIS

  use Text::Corpus::Summaries::Wikipedia;
  use Data::Dump qw(dump);
  my $corpus = Text::Corpus::Summaries::Wikipedia->new;
  $corpus->create;
  dump $corpus->getListOfXmlFiles;

DESCRIPTION

Text::Corpus::Summaries::Wikipedia creates corpora for single document summarization testing using the featured articles of various Wikipedias.

A criterion for an article in a Wikipedia to be featured is that it have a well written lead section, or introduction. So the featured articles of a Wikipedia can make an excellent corpus for testing single document summarization methods. This module creates a corpus from the featured articles of a Wikipedia by fetching and saving their content as HTML, text, and XML, with the appropriate sections labeled as either summary or body.

The Wikimedia featured articles page has the number of featured articles on various Wikipedias including links to their rating criteria (if they exist). For example, the English Wikipedia has an article on the criteria for a featured article and the criteria for a good introduction.

CONSTRUCTOR

`new`

The constructor new creates an instance of the Text::Corpus::Summaries::Wikipedia class with the following parameters:

languageCode

 languageCode => 'en'

languageCode is the language code of the Wikipedia from which the corpus of featured articles are to be created. The supported language codes are af:Afrikaans, ar:Arabic, az:Azerbaijani, bg:Bulgarian, bs:Bosnian, ca:Catalan, cs:Czech, de:German, el:Greek, en:English, eo:Esperanto, es:Spanish, eu:Basque, fa:Persian, fi:Finnish, fr:French, he:Hebrew, hr:Croatian, hu:Hungarian, id:Indonesian, it:Italian, ja:Japanese, jv:Javanese, ka:Georgian, kk:Kazakh, km:Khmer, ko:Korean, li:Limburgish, lv:Latvian, ml:Malayalam, mr:Marathi, ms:Malay, mzn:Mazandarani, nl:Dutch, nn:Norwegian (Nynorsk), no:Norwegian (Bokm?l), pl:Polish, pt:Portuguese, ro:Romanian, ru:Russian, sh:Serbo-Croatian, simple:Simple English, sk:Slovak, sl:Slovenian, sr:Serbian, sv:Swedish, sw:Swahili, ta:Tamil, th:Thai, tl:Tagalog, tr:Turkish, tt:Tatar, uk:Ukrainian, ur:Urdu, vi:Vietnamese, vo:Volap?k, and zh:Chinese. If the language code is all, then the corpus for each supported language is created (which takes a long time). The default is en.

corpusDirectory

 corpusDirectory => 'cwd'

corpusDirectory is the corpus directory that the summaries and articles will be stored in; the directory is created if it does not exist. The default is the cwd.

A language subdirectory is created at corpusDirectory/languageCode that will contain the directories log, html, unparsable, text, and xml. The directory log will contain the file log.txt that all errors, warnings, and informational messages are logged to using Log::Log4perl. The directory html will contain copies of the HTML versions of the featured article pages fetched using LWP. The directory text will contain two files for each article; one file will end with _body.txt and contain the body text of the article, the other will end with _summary.txt and will contain the summary. The directory unparsable will contain the HTML files that could not be parsed into body and summary sections. All files are UTF-8 encoded.

METHODS

`create`

The method create fetches the featured articles and creates the text and XML versions of the files.

  use Text::Corpus::Summaries::Wikipedia;
  use Data::Dump qw(dump);
  my $corpus = Text::Corpus::Summaries::Wikipedia->new;
  $corpus->create;
  dump $corpus->getListOfXmlFiles;
  dump $corpus->getListOfTextFiles;

maxProcesses

 maxProcesses => 1

maxProcesses is the maximum number of processes that can be running simultaneously to parse the files. Parsing the files for the summary and body sections may be computational intensive so the module Forks::Super is used for parallelization. The default is one.

test

 test => 0

If test is a positive integer than it will be treated as the maximum number of pages that may be fetched and parsed. The default is zero, meaning all possible pages are fetched and parsed.

`recreate`

The method recreate recreates the text and XML versions of the files from the list of previously fetched HTML files in the html directory.

  use Text::Corpus::Summaries::Wikipedia;
  use Data::Dump qw(dump);
  my $corpus = Text::Corpus::Summaries::Wikipedia->new;
  $corpus->recreate;
  dump $corpus->getListOfXmlFiles;
  dump $corpus->getListOfTextFiles;

maxProcesses

 maxProcesses => 1

test

 test => 0

If test is a positive integer than it will be treated as the maximum number of pages that may be parsed. The default is zero, meaning all possible pages are parsed.

`getListOfTextFiles`

The method getListOfTextFiles returns an array reference with each item in the list having the form {body => 'path_to_body_file', summary => 'path_to_summary_file'}.

  use Text::Corpus::Summaries::Wikipedia;
  use Data::Dump qw(dump);
  my $corpus = Text::Corpus::Summaries::Wikipedia->new;
  $corpus->create;
  dump $corpus->getListOfTextFiles;

`getListOfXmlFiles`

The method getListOfXmlFiles returns an array reference containing the path to each XML file.

  use Text::Corpus::Summaries::Wikipedia;
  use XML::Simple;
  use Data::Dump qw(dump);
  my $corpus = Text::Corpus::Summaries::Wikipedia->new;
  foreach my $xmlFile (@{$corpus->getListOfXmlFiles})
  {
    my $article;
    eval { $article = XMLin ($xmlFile) };
    if ($@) { dump \$@; } else { dump $article; }
  }

XML FORMAT

The XML files are created using XML::Code with the simple structure outlined below:

  <document>
    <title>The Article Title</title>
    <summary>
      <p>This is the first paragraph of the summary.</p>
      <p>This is the second paragraph of the summary.</p>
    </summary>
    <body>
      <section>
        <header>Head of first section</header>
        <p>First paragraph of this section.</p>
        <p>Second paragraph of this section.</p>
      </section>
      <section>
        <p>First paragraph of this section.</p>
        <p>Second paragraph of this section.</p>
        <section>
          <header>Head of  sub-section</header>
          <p>First paragraph of this sub-section.</p>
          <p>Second paragraph of this sub-section.</p>
        </section>
      </section>
    </body>
  </document>

EXAMPLE

The following example computes and prints the median, mean, and standard deviation of the fraction of words (ignoring repeats) in a summary that also occur in the body of the text for all the articles in the corpora.

  use Text::Corpus::Summaries::Wikipedia;
  use Statistics::Descriptive;
  use File::Slurp;
  use Encode;

  my $corpus = Text::Corpus::Summaries::Wikipedia->new;
  my $statistics = Statistics::Descriptive::Full->new;
  foreach my $textFilePair (@{$corpus->getListOfTextFiles})
  {
    my $summary = lc decode ('utf8', read_file ($textFilePair->{summary}, binmode => ':raw'));
    my %summaryWords = map {($_, 1)} split (/\P{Letter}/, $summary);
    my $totalUniqueSummaryWords = keys %summaryWords;
    next unless $totalUniqueSummaryWords;

    my $body = lc decode ('utf8', read_file ($textFilePair->{body}, binmode => ':raw'));
    map {delete $summaryWords{$_}} split (/\P{Letter}/, $body);
    my $totalUniqueSummaryWordsNotInBody = keys %summaryWords;

    $statistics->add_data (1 - $totalUniqueSummaryWordsNotInBody / $totalUniqueSummaryWords);
  }

  print 'count: ', $statistics->count(), "\n";
  print 'median: ', $statistics->median(), "\n";
  print 'mean: ', $statistics->mean(), "\n";
  print 'standard deviation: ', $statistics->standard_deviation(), "\n";

SCRIPTS

The script create_summary_corpus.pl makes a corpus for summarization testing using this module.

INSTALLATION

Use CPAN to install the module and all its prerequisites:

  perl -MCPAN -e shell
  >install Text::Corpus::Summaries::Wikipedia

BUGS

This module creates corpora by parsing Wikipedia pages, the xpath expressions used to extract links and text will become invalid as the format of the various pages changes, causing some corpora not to be created.

Please email bugs reports or feature requests to bug-text-corpus-summaries-wikipedia@rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Text-Corpus-Summaries-Wikipedia. The author will be notified and you can be automatically notified of progress on the bug fix or feature request.

AUTHOR

 Jeff Kubina<jeff.kubina@gmail.com>

COPYRIGHT

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

KEYWORDS

corpus, information processing, summaries, summarization, wikipedia

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