Question

I have two multidimensional arrays which store x and y coordinates I am trying to merge together into a single array while preserving the x value but adding together the y values.

Array 1:

Array(
[0] => Array
    (
        [x] => 1327449600000
        [y] => 5
    )

[1] => Array
    (
        [x] => 1327450500000
        [y] => 1
    )

Array 2:

 Array(
[0] => Array
    (
        [x] => 1327449600000
        [y] => 1
    )

[1] => Array
    (
        [x] => 1327450500000
        [y] => 3
    )

So the combined outcome would be:

 Array(
[0] => Array
    (
        [x] => 1327449600000
        [y] => 6
    )

[1] => Array
    (
        [x] => 1327450500000
        [y] => 4
    )

Any help would be greatly appreciated.

Answer 1

function add_array($a1, $a2) {
    $c = count($a1);
    for ($i=0;$i<$c;$i++) {
        if (isset($a2[$i]) && isset($a2[$i]['y'])) {
            $a1[$i]['y'] += $a2[$i]['y'];
        }
    }
    return $a1;
}