How to sum all column values in multi-dimensional array?

Question

How can I add all the columnar values by associative key? Note that key sets are dynamic.

Input array:

Arr         


        

Answer 1

Here's a version where the array keys may not be the same for both arrays, but you want them all to be there in the final array.

function array_add_by_key( $array1, $array2 ) {
    foreach ( $array2 as $k => $a ) {
        if ( array_key_exists( $k, $array1 ) ) {
            $array1[$k] += $a;
        } else {
            $array1[$k] = $a;
        }
    }
    return $array1;
}