multidimensional array array_sum

Question

I have seen various posted about this question so am aware some answers to this may exist. however I am none the wiser after reading these.

I have an array that is

Answer 1

You can do this using array_map() and select the vatAmount column first:

$totalVatAmount = array_sum(array_map(function($account_invoices) { 
    return $account_invoices['vatAmount']; 
}, $account_invoices));

Of course, internally this performs a double loop; it's just that you don't see it inside the code. If you use array_reduce() then you can get rid of one loop:

$totalVatAmount = array_reduce($account_invoices,
     function($totalAmount, $item) {
         $totalAmount += $item['vatAmount'];
            return $totalAmount;
     },
   0
);

However, if speed is the only interest, you should use foreach. Because there is no function calls used to calculate the final sum. This solution is faster than other solution.

$totalVatAmount = 0;
foreach ($account_invoices as $item) {
    $totalVatAmount += $item['vatAmount'];
}