NAME

Text::Distill - Quick texts compare, plagiarism and common parts detection

VERSION

Version 0.4

SYNOPSIS

 use Text::Distill qw(Distill);

 my $DistilledText1 = Distill($text1);
 my $DistilledText2 = Distill($text2);

 $DistilledText1 eq $DistilledText2 ? print("Equal") : print("Not equal");

or

 use Text::Distill;

 my $FileFormat = Text::Distill::DetectBookFormat($FilePath);
 die "Not a fb2.zip file" if $FileFormat ne 'fb2.zip';

 my $Text = Text::Distill::ExtractTextFromFB2File($FilePath);
 my $Gems = TextToGems($Text);

 my $VURL = 'http://partnersdnld.litres.ru/copyright_check_by_gems/';
 my $TextInfo = Text::Distill::GemsValidate($Gems,$VURL);

 die "Copyright-protected content" if $TextInfo->{verdict} eq 'protected';

Distilling gems from text

TextToGems($UTF8TextString)

Transforms a text (valid UTF8 expected) into an array of 32-bit hash-summs (Jenkins's Hash). Text is at first flattened the hard way (something like soundex, see Distill below), than splitted into fragments by statistically choosen sequences. First and the last fragments are rejected, short fragments are rejected as well, from remaining strings calc hashes and returns reference to them in the array.

What you really need to know is that TextToGem's from exactly the same texts are eqlal, texts with small changes have similar "gems" as well. And if two texts have 3+ common gems - they share some text parts, for sure. This is somewhat close to "Edit distance", but fast on calc and indexable. So you can effectively search for citings or plagiarism. Choosen split-method makes average detection segment about 2k of text (1-2 paper pages), so this package will not normally detect a single equal paragraph. If you need more precise match extended @Text::Distill::SplitChars with some sequences from SeqNumStats.xlsx on GitHub, I guiess you can get down to parts of about 300 chars without problems. Just don't forget to lower $Text::Distill::MinPartSize as well and keep in mind GemsValidate will break if you play with $MinPartSize and @SplitChars.

Should return about one 32-bit jHash from every 2kb of source text (may vary depending on the text thou).

 my $Gems = TextToGems($String);
 print join(',',@$Gems);

Distill($UTF8TextString)

Transforming the text (valid UTF8 expected) into a sequence of 1-8 numbers (string as well). Internally used by TextToGems, but you may use it's output with standart "edit distance" algorithm, like Text::Levenshtein. Distilled string is shorter, so you math will go much faster.

At the end works somewhat close to 'soundex' with addition of some basic rules for cyrillic chars, pre- and post-cleanup and utf normalization. Drops strange sequences, drops short words as well (how are you going to make you plagiarism without copying the long words, huh?)

 $Distilled = Distill($Text);  # $Distilled should be ~60% shorter than $Text

Remote validation

There is at least one open service to check your text against known text database, docs are here: https://goo.gl/xmFMdr.

GemsValidate(\@Gems, $Url)

Checks your gems against remote database, returns overall verdict and a structure with info on found titles

Service functions

ExtractTextFromFB2File($FilePath)

Function receives a path to the fb2-file and returns all significant text from the file as a string

ExtractTextFromFB3File($FilePath)

Function receives a path to the fb3-file and returns all significant text from the file as a string

ExtractTextFromTXTFile($FilePath)

Function receives a path to the text-file and returns all significant text from the file as a string

ExtractTextFromDocFile($FilePath)

Function receives a path to the doc-file and returns all significant text from the file as a string

ExtractTextFromDOCXFile($FilePath)

Function receives a path to the docx-file and returns all significant text from the file as a string

ExtractTextFromEPUBFile($FilePath)

Function receives a path to the epub-file and returns all significant text from the file as a string

DetectBookFormat($FilePath, $Format)

Function detects format of an e-book and returns it. You may suggest the format to start with, this wiil speed up the process a bit (not required).

$Format can be 'fb2.zip', 'fb2', 'doc.zip', 'doc', 'docx.zip', 'docx', 'epub.zip', 'epub', 'txt.zip', 'txt', 'fb3', 'fb3'

Internals:

Receives a path to the file and checks whether this file is ...

CheckIfDocZip() - MS Word .doc in zip-archive

CheckIfEPubZip() - Electronic Publication .epub in zip-archive

CheckIfDocxZip() - MS Word 2007 .docx in zip-archive

CheckIfFB2Zip() - FictionBook2 (FB2) in zip-archive

CheckIfTXT2Zip() - text-file in zip-archive

CheckIfEPub() - Electronic Publication .epub

CheckIfDocx() - MS Word 2007 .docx

CheckIfDoc() - MS Word .doc

CheckIfFB2() - FictionBook2 (FB2)

CheckIfFB3() - FictionBook3 (FB3)

CheckIfTXT() - text-file

REQUIRED MODULES

 Digest::JHash;
 XML::LibXML;
 XML::LibXSLT;
 Encode::Detect;
 Text::Extract::Word;
 HTML::TreeBuilder;
 OLE::Storage_Lite;
 Text::Unidecode (v1.27 or later);
 Unicode::Normalize (v1.25 or later);
 Archive::Zip
 Encode;
 Carp;
 LWP::UserAgent;
 JSON::XS;
 File::Temp;

SCRIPTS

plagiarism_check.pl - checks your ebook againts known texts database

Script uses check_by_gems API (https://goo.gl/xmFMdr). You can select any "check service" provider with CHECKURL (see below), by default text checked with LitRes copyright-check service: http://partnersdnld.litres.ru/copyright_check_by_gems/

USAGE

 > plagiarism_check.pl FILEPATH [CHECKURL] [--full-info] [--help]

EXAMPLE

 > plagiarism_check.pl /home/file.epub --full-info

PARAMS

FILEPATH path to file for check

CHECKURL url of validating API to check file with. By default: http://partnersdnld.litres.ru/copyright_check_by_gems/

--full-info show full info of checked

--help show this information

OUTPUT

Ebook statuses explained:

protected there are either copyrights on this book or it is forbidden for distribution by some other reason (racist content, etc)

free ebook content owner distributes it for free (but content may still be protected from certan kind use)

public_domain this it public domain, no restrictions at all

unknown service have has no valid info on this text

AUTHOR

Litres.ru, <gu at litres.ru> Get the latest code from https://github.com/Litres/TextDistill

BUGS

Please report any bugs or feature requests to https://github.com/Litres/TextDistill/issues.

SUPPORT

You can find documentation for this module with the perldoc command.

    perldoc Text::Distill

You can also look for information at:

LICENSE AND COPYRIGHT

Copyright (C) 2016 Litres.ru

The GNU Lesser General Public License version 3.0

Text::Distill is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3.0 of the License.

Text::Distill is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

Full text of License http://www.gnu.org/licenses/lgpl-3.0.en.html.