PHP - Output only lines with duplicate words (singular or plural)

output-duplicate-lines.php

<?php    

// Ravexina
// A more canonical answer has been sent here: "https://stackoverflow.com/questions/45528160/output-only-lines-with-duplicate-words"
// The included class.php is from here: "https://gist.github.com/tbrianjones/ba0460cc1d55f357e00b"

// This code tries to address the OP's comments 

$text = "This is a best website of all the websites out there
    This is a great website
    Here is a website I found while looking for websites
    Website is a cool new word
    Playing blackjack on the blackjack table.
    Here's a blackjack game.
    My favorite blackjack and blackjack.
    Something else with else and else duplicates.
    Wow a great blackjack game.";

// helps us pluralize all words, so we can check the duplicates 
include('class.php'); 

// search for a specific term
$search_for = 'blackjack';

// loop into each line one by one
foreach(explode("\n", $text) as $line)
{
        // remove special characters
        $tline = preg_replace('/[^A-Za-z0-9\-\s]/', '', $line);

        // create a list of words from current line
        $words_list = preg_split('/\s+/', strtolower(trim($tline)));

       // skip this loop if the word does not exist in this line
       if(! in_array($search_for, $words_list))
            continue;

        // convert all singular words to plural
        foreach($words_list as $word)
        {
                $w[] = Inflect::pluralize($word);
        }

         // if the count of words in this line was bigger that of unique
         // words then we got some duplicates, echo this line out
        if( count($w) > count(array_unique($w)) )
                echo $line . '</br>';

        // empty the array for next line
        $w = [];
}

// End of the file