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 like the following.

[0] => Array
    (
        [id] => 95659865986
        [invoiceNumber] => 6374324
        [invoiceTitle] => Monthly
        [invoiceStatus] => Paid
        [accountId] => 6235218753
        [totalExVat] => 158.95
        [dateCreated] => 1 Apr 2012
        [vatAmount] => 20.00
    )

All I wish to do is do array sum on the vatAmount values of this array.

As the following doesnt seem to be doing much.

(array_sum($account_invoices['vatAmount'])

Answer 1

If you have PHP 5.5+ you can do this without looping or using a callback (since function calls are relatively expensive) ... just use:

$sum = array_sum(array_column($account_invoices, 'vatAmount')); 

Answer 2

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 3

Just a way to do it:

$sum = 0;

foreach($account_invoices as $num => $values) {
    $sum += $values[ 'vatAmount' ];
}