Sum of Dynamic Multi-Dimension array in PHP - php

Question

I searched for few in-built methods and tried few logics from here and there but none can make me satisfied. I have created my own logic but is limited to a certain dimension of the array. I have managed to solve my problem for the project but as I said I am not satisfied.
Consider the array below:
$data = array
(
'0' => array
(
'0' => array
(
'make_ready' => '',
'ready_time' => '0.55',
'rate' => '46',
'no_of_run' => '',
'fixed_cost' => '',
'variable_cost' => '25.3',
'0' => array(
'kg' => 2.66,
'rate' => 11.4,
'fixed_cost' => '',
'variable_cost' => 30.32,
'0' => array(
'kg' => 2.66,
'rate' => 11.4,
'fixed_cost' => '',
'variable_cost' => 30.32,
),
),
),
),
'1' => array
(
'0' => array
(
'make_ready' => '1',
'ready_time' => '1.16',
'rate' => '36.47',
'no_of_run' => '',
'fixed_cost' => '36.47',
'variable_cost' => '42.31',
),
),
'2' => array
(
'make_ready' => '2',
'ready_time' => '0.29',
'rate' => '360',
'no_of_run' => '',
'fixed_cost' => '720',
'variable_cost' => '104.4',
),
'size' => '1000 X 1200 X 1190',
'up' => '3 X 4 / 17',
'unit' => '4',
'rate' => 16.32,
'fixed_cost' => '',
'variable_cost' => 65.28,
);
Problem:
I want to sum up all the values of array element where key is 'variable_cost', no matter how deep (in terms of dimension) is the array. Basically like a loop that can scan all the elements and do 'sum' if key matches.
I would like someone to help/suggest any logic where the calculations can be done till nth dimension.
For example like the movie Inception, in which they can go
dream->with in a dream->to nth number of dream.
and come out with the sum of 'variable_cost'. Hope you guys can understand the question here.
Thank you.

Answer 1

You will need to use a recursive function to sum all the variable_cost values:
function sum_variable_cost( $data, $total=0) {
foreach ($data as $key => $item) {
if (is_array($item)) {
$total = sum_variable_cost($item, $total);
} else if ($key=='variable_cost') {
//echo $key . " " . $item . "\n";
$total += $item;
}
}
return $total;
}
echo sum_variable_cost( $data );
Basically it loops through the array and sees if there are other arrays and only adds values that contain the key variable_cost.
If you uncomment the echo line it will show this output:
variable_cost 25.3
variable_cost 30.32
variable_cost 30.32
variable_cost 42.31
variable_cost 104.4
variable_cost 65.28
297.93