If array value is repeated in another array, combine both arrays - php

Question

I have several arrays that I want to check for a repeated value and if the value is found to be repeated in one of the other arrays, then combine both of those arrays together.
I give an example below of 2 arrays that have repeated values.
example: the value in purchase_order_number is the same in both arrays below. They are not unique values. But the values in tracking_number are unique.
I want to check if the value in purchase_order_number is repeated in another array. If the same value is found in another array, then combine both of those arrays into 1 array.
I'm trying to get the value in tracking_number and service combined into a single array when the value in purchase_order_number is the same in 2 or more arrays.
Example arrays below.
not combined
array (
'data' =>
array (
15 =>
array (
'type' => 'Tracking',
'id' => 2830143,
'attributes' =>
array (
'tracking_number' => '1Z5270560360309870',
'service' => 'UPS',
'order_id' => 2606218,
'purchase_order_number' => '7249491',
'recipient_attempts' => 1,
),
),
16 =>
array (
'type' => 'Tracking',
'id' => 2830144,
'attributes' =>
array (
'tracking_number' => '1Z5270560361740866',
'service' => 'UPS',
'order_id' => 2606218,
'purchase_order_number' => '7249491',
'recipient_attempts' => 1,
),
),
),
)
Example given below of how I need to combine the two above arrays.
Combined
array (
'data' =>
array (
16 =>
array (
'type' => 'Tracking',
'id' => 2830144,
'attributes' =>
array (
'tracking' =>
array (
0 =>
array (
'tracking_number' => '1Z5270560360309870',
'service' => 'UPS',
),
1 =>
array (
'tracking_number' => '1Z5270560361740866',
'service' => 'UPS',
),
),
'order_id' => 2606218,
'purchase_order_number' => '7249491',
'recipient_attempts' => 1,
),
),
),
)

Answer 1

Here's a reduce based solution with caveats:
$arr['data'] = array_reduce($arr['data'], function ($out, $item) {
// keys we want to extract
static $tracking_keys = ['tracking_number' => '', 'service' => ''];
// yank tracking keys from attributes
$tracking = array_intersect_key($item['attributes'], $tracking_keys);
$item['attributes'] = array_diff_key($item['attributes'], $tracking_keys);
// insert to new array based on order number
$order_no = $item['attributes']['purchase_order_number'];
if (!isset($out[$order_no])) {
$item['attributes']['tracking'] = [$tracking];
$out[$order_no] = $item;
} else {
array_push($out[$order_no]['attributes']['tracking'], $tracking);
}
return $out;
}, []);
Keys in 'data' are not retained and 'id' is set by the first item.