Group and sum data in fourth level of multidimensional array

Question

I have this multidimensional array that I need to find how many items for any SKU are sold.

How I can do?

    [Orders] => Array(
        [0] => Array(
            [transaction_id] => xxxx
            [date] => 1616277653
            [currency] => EUR
            [items] => Array(
                    [0] => Array(
                            [title] => Title
                            [quantity] => 200
                            [price] => 2.1
                            [sku] => 1T.810BK
                        )
                    [1] => Array(
                            [title] => Title
                            [quantity] => 250
                            [price] => 1.78
                            [sku] => 1090.005BK
                        )
              )
        )
        [1] => Array(
                [transaction_id] => 78079
                [date] => 1616597838
                [currency] => EUR
                [items] => Array(
                        [0] => Array
                            (
                                [title] => title
                                [quantity] => 3
                                [price] => 118.3
                                [sku] => 1.DIYBOX.ULT.638RE
                            )
                )
        )
)

For the moment I was using a function with array_walk_recursive inside, to extract all the values of a Key SKU. But in this way I cannot associate it with the value of the quantity.

So this can't be the solution, unless I can't pass 2 Key variables inside the function. It can be done?

This is the function that I use at this moment:

        function array_value_recursive($key, array $arr){
                $val = array();
                array_walk_recursive($arr, function($v, $k) use($key, &$val){
                    if($k == $key) array_push($val, $v);
                });
                return count($val) > 1 ? $val : array_pop($val);
        }

        array_value_recursive('sku', $GetPendingOrders_obj);

I'm not sure if passing two keys is the ideal solution. How do you think I can solve the problem of finding the quantity of the SKU sold?

Answer 1

array_walk_recursive is indeed the way to go, however, it gets a little tricky with PHP associative arrays as they are dictionaries and maintain keys in sequential order, meaning, keys order are the same as the way they were inserted in the first place. To make it work regardless of the order of quantity and sku keys, maintain global variables $sku and $qt and switch to the default values whenever you find their pair.

Snippet:

<?php

$sku = '';
$qt = -1;
$result = [];
    
array_walk_recursive($arr, function($v, $k) use(&$sku,&$qt,&$result) {
    if($k === 'quantity'){
        if($sku !== ''){
            $result[ $sku ] = $result[ $sku ] ?? 0;
            $result[ $sku ] += $v;
            $sku = '';
        }else {
            $qt = $v;
        }
    }elseif($k === 'sku'){
        if($qt !== -1){
            $result[ $v ] = $result[ $v ] ?? 0;
            $result[ $v ] += $qt;
            $qt = -1;
        }else{
            $sku = $v;
        }
    }
});
 
 
print_r($result);

Answer 2

Another alternative would be to use a combination of array_column to get all items first. Then merge all sub items into just one multi dimensional using array_merge_recursive with splat. And finally, again array_column to get the sku and quantity:

$items = array_column(array_merge_recursive(... array_column($data['Orders'], 'items')), 'quantity', 'sku');

In the end, you'll key-pair value with sku and quantity.

Answer 3

Recursive techniques are unnecessary overhead for this task. You do not need to visit every leaf-node to generate the desired output.

The other answers also do not bother to sum skus which are encountered more than once (in separate orders). Here is proof: https://3v4l.org/ZCRTu

I've expanded your sample data to include an sku which occurs more than once. This way you can see that quantities are actually summed where necessary.

Code: (Demo)

$result = [];
foreach ($data['Orders'] as $order) {
    foreach ($order['items'] as $item) {
        $result[$item['sku']] = ($result[$item['sku']] ?? 0) + $item['quantity'];
    }
}
var_export($result);

---

If you prefer functional programming, you will need to reduce the number of levels (in other words, use a classic flattening technique -- I prefer merge&spread) before you can group&sum.

Code: (Demo)

var_export(
    array_reduce(
        array_merge(
            ...array_column($data['Orders'], 'items')
        ),
        function($carry, $item) {
            $carry[$item['sku']] = ($carry[$item['sku']] ?? 0) + $item['quantity'];
            return $carry;
        }
    )
);

Output from either snippet:

array (
  '1T.810BK' => 200,
  '1090.005BK' => 550,
  '1.DIYBOX.ULT.638RE' => 3,
)