如何计算数组中的重复值？

Question

I have a series of user data which each one is a list of comma separate values like italian, english. So first of all I want to list each of them and that it is fine and works. But these values could be repeated and it is ok yet I would like to know the number of the repeat values in order to be able to says: American = 2. The code below shows me

Duplicates count: 5

But actually I should have only 2 duplicates as I can see from the admin panel

$stack = array();
$blogusers = get_users( 'orderby=nicename&role=author' );
foreach ( $blogusers as $user ) {
    $descTokens = explode(',', $user->user_description);
    $stack = array_merge($stack, $descTokens);
}
$count_values = array();
foreach ($stack as $a) {
    @$count_values[$a]++;
}
echo 'Duplicates count: '.count($count_values);

If I do print_r($count_values) i get

Array ( [francese] => 1 [ matematica] => 2 [ inglese] => 1 [fisica] => 1 [ latino] => 1 ) Duplicates count: 5

And those aren't repeated strings

Answer 1

Add this at the end of your code to only have duplicates in $count_values

$total_duplicates = 0;
foreach ($count_values as $key=>$count) {
    if($count<=1){
        unset($count_values[$key]);
    }else{
        $total_duplicates += $count;
    }
}

This will remove any entries that are not duplicate (occuring once) via unset(). Also $total_duplicates will give you the total count of duplicates.

To output that as html do this:

echo '<p>You have '.$total_duplicates.' duplicates.</p>';
foreach ($count_values as $key=>$count) { 
    echo '<li>'.$key.' '.$count.'</li>'; 
}