比较嵌套数组是否相等

Question

Given the following arrays:

$array[0]['tid'] = 'valueX';
$array[1]['tid'] = 'valueY';

$array2[0]['tid'] = 'valueZ';
$array2[1]['tid'] = 'valueY';

My goal is to check if any of the values in $array are in $array2

Below is what I came up with but I'm wondering if there is a easier / better solution? Maybe something that gets only the values of an array or removes the 'tid' key.

foreach($array as $arr) {
    $arr1[] = $arr['tid'];
}

$flag = 0;

foreach($array2 as $arr) {
    if( in_array( $arr['tid'], $arr1 ) ) {
        $flag++;
    }
}
echo $flag; // number of duplicates

Answer 1

One way you could approach this:

$extractor = function($row) { return $row['tid']; };
echo "Duplicates: ".count(array_intersect(
    array_map($extractor, $array),
    array_map($extractor, $array2)
));

What this does is pull out the tid value from each array element on both arrays, then intersecting the results (to find values present in both arrays). It might make sense to tweak it a bit or keep the interim results around depending on what exactly you intend to do.

See it in action.