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

I would use array_map to reduce the array to only what is needed. Bear in mind, this will only work with PHP 5.3 onwards.

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

Answer 2

Just another way to do this using array_reduce:

$vatMount = array_reduce($account_invoices, function($total, $value) {
    return $total + $value['vatAmount'];
});

Answer 3

A way to do this using a PHP 5.3+ anonymous function

$account_invoices = array(
    0 => array(
        'id' => '95659865986',
        'invoiceNumber' => '6374324',
        'invoiceTitle' => 'Monthly',
        'invoiceStatus' => 'Paid',
        'accountId' => '6235218753',
        'totalExVat' => 158.95,
        'dateCreated' => '1 Apr 2012',
        'vatAmount' => 20.00
    ),
    1 => array(
        'id' => '95659865987',
        'invoiceNumber' => '6374325',
        'invoiceTitle' => 'Monthly',
        'invoiceStatus' => 'Paid',
        'accountId' => '6235218753',
        'totalExVat' => 208.95,
        'dateCreated' => '1 May 2012',
        'vatAmount' => 25.00
    ),
);


$sumDetail = 'vatAmount';
$totalVAT = array_reduce($account_invoices,
           function($runningTotal, $record) use($sumDetail) {
               $runningTotal += $record[$sumDetail];
               return $runningTotal;
           },
           0
);
echo $totalVAT;

Answer 4

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'];
}