计算不同类别ID的数量？

Question

So I have the following array like this :

[0] => Array
        (
            [id] => 10
            [rec_id] => 4
            [mid] => a:2:{i:0;s:1:"2";i:1;s:1:"5";}
            [cid] => 5
            [lang] => geo
            [title] => ჯიმი მორისონი გაცოცხლდა
            [intro] =>
            [img] => xhdvlmvogeujm76.jpg
        [text] =>

        )

    [1] => Array
        (

            [id] => 7
            [rec_id] => 6
            [mid] => a:2:{i:0;s:1:"2";i:1;s:1:"5";}
            [cid] => 3
            [lang] => geo
            [title] => 70 people died
            [intro] =>
            [img] => as554ghbvwe5.jpg
        [text] =>

        )




)

What I want to do is count how many different Cid (category id) are in my items. Let's say I have 5 items with each a different cid, then counter should return 5, if 3 out of these 5 have the same cid, then it returns 3 and so on. I've been tempering with foreach() but no luck . here what i tried

foreach ($data as $k=>$v)
{
    if ($v['cid']!=$v['cid']){
        $counter=$counter+1;
    }
}

Answer 1

If you're using PHP 5.5+ you can use

$uniqueCids = array_unique(
    array_column(
        $myArray,
        'cid'
    )
);

For PHP < 5.5, you can use

$uniqueCids = array_unique(
    array_map(
        function($value) {
            return $value['cid'];
        },
        $myArray
    )
);

Then just do

$uniqueCidCount = count($uniqueCids);