TextRank 
extract relevant keywords from a given text
How to use it
In order to use the class, you must instance a Config object.
<?php
require __DIR__ . "/vendor/autoload.php";
use \crodas\TextRank\Config;
use \crodas\TextRank\TextRank;
$config = new Config;
$textrank = new TextRank($config);
$keywords = $textrank->getKeywords($some_long_text);
var_dump($keywords);It is possible to get better results by adding few information about the language (stopword list, stemmer with pecl install stem).
<?php
require __DIR__ . "/vendor/autoload.php";
use \crodas\TextRank\Config;
use \crodas\TextRank\TextRank;
use \crodas\TextRank\Stopword;
$config = new Config;
$config->addListener(new Stopword);
$textrank = new TextRank($config);
$keywords = $textrank->getKeywords($some_long_text);
var_dump($keywords);By doing this it will detect the language of the text and will remove common words (from the stopword list). If ext-stem is available the results will be even better.
Summarize large texts
This class is also capable of summarizing long texts
$config = new \crodas\TextRank\Config;
$config->addListener(new \crodas\TextRank\Stopword);
$analizer = new \crodas\TextRank\Summary($config);
$summary = $analizer->getSummary($text); $summary is at most 5% of the sentences of the text.