How to group subarrays and perform conditional calculations? - php

Question

I need to group my subarray using product_id and perform some conditional arithmetic.
If moving_type is 1 then the overall product_number tally for the current product_id should be increased by the product_number. Alternatively, if the moving_type is 2 then the overall product_number tally should be decreased by the product_number value.
This is my input array:
Array
(
[0] => Array
(
[id] => 1
[product_id] => 4
[product_number] => 10
[moving_type] => 1
)
[1] => Array
(
[id] => 1
[product_id] => 5
[product_number] => 10
[moving_type] => 1 // product addition
)
[2] => Array
(
[id] => 1
[product_id] => 5
[product_number] => 2
[moving_type] => 2 // product minus
)
)
My desired result is:
Array
(
[0] => Array
(
[id] => 1
[product_id] => 4
[product_number] => 10
)
[1] => Array
(
[id] => 1
[product_id] => 5
[product_number] => 8 // as 10-2
)
)

Answer 1

Most efficiently use temporary keys based on product_id to determine if you are performing arithmetic between two values or merely declaring the first occurring value for the product_id.
If it is the first occurrence, just slice the first three rows off the row and preserve the keys (that's the true part).
If it is not the first occurrence of product_id, then you will only need to update the product_number element. Determine the correct operation based on the moving_type value -- using that, multiply the product_number by either 1 or -1 and add that generated value to the stored value.
When the loop is finished, you can reindex the resulting array with array_values().
Code: (Demo)
$array = [
['id' => 1, 'product_id' => 4, 'product_number' => 10, 'moving_type' => 1],
['id' => 1, 'product_id' => 5, 'product_number' => 10, 'moving_type' => 1],
['id' => 1, 'product_id' => 5, 'product_number' => 2, 'moving_type' => 2]
];
foreach ($array as $row) {
if (!isset($result[$row['product_id']])) {
$result[$row['product_id']] = array_slice($row, 0, 3, true);
} else {
$result[$row['product_id']]['product_number'] += ($row['moving_type'] == 1 ? 1 : -1) * $row['product_number'];
}
}
var_export(array_values($result));
Output:
array (
0 =>
array (
'id' => 1,
'product_id' => 4,
'product_number' => 10,
),
1 =>
array (
'id' => 1,
'product_id' => 5,
'product_number' => 8,
),
)

Answer 2

You could use a foreach() loop. Inside it, you could create a new array using product_id as key. You could use *=-1 to change the sign of the product_number, and if the key already exists, add the current product_number to the existing one.
$array = array(
array('id' => 1, 'product_id' => 4, 'product_number' => 10, 'moving_type' => 1),
array('id' => 1, 'product_id' => 5, 'product_number' => 10, 'moving_type' => 1),
array('id' => 1, 'product_id' => 5, 'product_number' => 2, 'moving_type' => 2)
);
$final = [];
foreach ($array as $item) {
$pid = $item['product_id'] ;
if ($item['moving_type'] == 2) $item['product_number'] *= -1;
unset($item['moving_type']);
if (!isset($final[$pid])) { $final[$pid] = $item ; }
else {
$final[$pid]['product_number'] += $item['product_number'] ;
}
}
$final = array_values($final);
print_r($final);
Output:
Array
(
[0] => Array
(
[id] => 1
[product_id] => 4
[product_number] => 10
)
[1] => Array
(
[id] => 1
[product_id] => 5
[product_number] => 8
)
)