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't do this directly with array_sum, which would sum everything in the array.

You can do it with a loop:

$sum = 0;
foreach($items as $item)
    $sum += $item['vatAmount'];

or you can filter the array (in this case it isn't very convenient, but if you had to calculate, say, S&H expenses plus VAT plus..., from each single item, and then sum...):

// Input: an array (element #n of array of arrays), output: VAT field
function getVAT($item)
{
    return $item['vatAmount'];
}

// Array with all VATs
$vats = array_map('getVAT', $items);

$sum = array_sum($vats);