Sum values from deep columns of a 3d array to produce a flat associative array

Question

This is the original main array:

Array (

[0] => Array

    (
        [subtotal] => 0.6000
        [taxes] => 0.0720
        [charged_amount] => 0.6720
        [total_discount] => 0.0000
        [provinceName] => BC
        [store_key] => 1
        [store_id] => 5834
        [categories] => Array
            (
                [2] => 0.6000
                [4] => 0
                [3] => 0
            )

    )

[1] => Array
    (
        [subtotal] => 29.8500
        [taxes] => 2.3270
        [charged_amount] => 20.2370
        [total_discount] => 11.9400
        [provinceName] => MB
        [store_key] => 9
        [store_id] => 1022
        [categories] => Array
            (
                [2] => 0
                [4] => 29.8500
                [3] => 0
            )

    )

[2] => Array
    (
        [subtotal] => 0.3000
        [taxes] => 0.0390
        [charged_amount] => 0.3390
        [total_discount] => 0.0000
        [provinceName] => NB
        [store_key] => 8
        [store_id] => 1013
        [categories] => Array
            (
                [2] => 0.3000
                [4] => 0
                [3] => 0
            )

    )

[3] => Array
    (
        [subtotal] => 24.3100
        [taxes] => 1.1830
        [charged_amount] => 10.2830
        [total_discount] => 15.2100
        [provinceName] => NL
        [store_key] => 4
        [store_id] => 3033
        [categories] => Array
            (
                [2] => 24.3100
                [4] => 0
                [3] => 0
            )

    )

[4] => Array
    (
        [subtotal] => 1116.3400
        [taxes] => 127.6960
        [charged_amount] => 1110.0060
        [total_discount] => 134.0300
        [provinceName] => ON
        [store_key] => 2
        [store_id] => 1139
        [categories] => Array
            (
                [2] => 85.7300
                [4] => 143.2800
                [3] => 887.3300
            )

    )

[5] => Array
    (
        [subtotal] => 10.8500
        [taxes] => 1.4100
        [charged_amount] => 12.2600
        [total_discount] => 0.0000
        [provinceName] => ON
        [store_key] => 5
        [store_id] => 1116
        [categories] => Array
            (
                [2] => 10.8500
                [4] => 0
                [3] => 0
            )

    )   

)

I just need to add the values of the array [categories] with same keys and use it further to print the total, but not getting correct output, can someone help me out to get the desired result:

Desired result

An array with same keys but total of individual array values

Array ( [2] => 0.9000 [4] => 29.8500 [3] => 1.5 ) 

NOTE: Initial array is dynamic can have n number of key value pair

Thanks

Answer 1

The first thing that you need to do is iterate through the outer array. Then, for each row in the outer array, you and to iterate through each entry in the category element. So this means that we have two foreach loops. Inside the inner foreach, we simply set the value for the current index to be the value of the same index on a 'sum' array (if it doesn't already exist), or increment the value of that index if it already exists in the 'sum' array.

<?php
$sumArray = array();

foreach($outerArray as $row)
{
    foreach($row["categories"] as $index => $value)
    {
        $sumArray[$index] = (isset($sumArray[$index]) ? $sumArray[$index] + $value : $value);
    }
}
?>

Demo using your example array