In PHP, merge duplicate set of elements of an multidimensional array and sum the values of specific key

Question

I have following array where I am trying to merge the elements which has shelf and weight value as duplicate and sum the value of piece ke

Answer 1

If you absolutely have to do this in PHP, then something like:

$data = array(
    array(
        'shelf' => 'Left',
        'weight' => '10.000',
        'piece' => 1,
    ),
    array(
        'shelf' => 'Right',
        'weight' => '04.000',
        'piece' => 12,
    ),
    array(
        'shelf' => 'Right',
        'weight' => '04.000',
        'piece' => 4,
    ),
    array(
        'shelf' => 'Right',
        'weight' => '07.000',
        'piece' => 8,
    ),
);


$newData = array();
$result = array_reduce(
    $data,
    function($newData, $value) {
        $key = $value['shelf'].$value['weight'];
        if (!isset($newData[$key])) {
            $newData[$key] = $value;
        } else {
            $newData[$key]['piece'] += $value['piece'];
        }
        return $newData;
    },
    $newData
);
var_dump($result);

will work, but I really do believe that you're creating major performance problems for yourself with your whole approach to this problem