Merge array with same ID - php

Question

I have the following array
Array ( [id] => 1 [name] => [cat_name] => Food & Beverage [quantity] => 1
[price] => 25 [image] => books_image/calories_fat_carbohydrate.png )
Array ( [id] => 2 [name] => [cat_name] => Food & Beverage [quantity] => 5
[price] => 38 [image] => books_image/the_law_relating_to_food.png )
Array ( [id] => 3 [name] => [cat_name] => Food & Beverage [quantity] => 5
[price] => 19 [image] => books_image/it_starts_with_food.png )
Array ( [id] => 3 [name] => [cat_name] => Food & Beverage [quantity] => 2
[price] => 19 [image] => books_image/it_starts_with_food.png )
In a $_SESSION['cartitem'] object, and the key is id.
My problem is that i have duplicates with id=3 and my desired output would be
Array ( [id] => 1 [name] => [cat_name] => Food & Beverage [quantity] => 1
[price] => 25 [image] => books_image/calories_fat_carbohydrate.png )
Array ( [id] => 2 [name] => [cat_name] => Food & Beverage [quantity] => 5
[price] => 38 [image] => books_image/the_law_relating_to_food.png )
Array ( [id] => 3 [name] => [cat_name] => Food & Beverage [quantity] => 7
[price] => 19 [image] => books_image/it_starts_with_food.png )
Basically merging by same id and adding the quantity field. Is there an easy way to do this in php?
I dont want to remove duplicates. The duplicates to me are important since they have quantities in which i need to add them.

Answer 1

Here you go:
// DEFINE SORTING CRITERIA
function sort_ids($a, $b) {
return $a['id'] > $b['id'];
}
// DEFINE ARRAY OF ARRAYS
$arrays = array(
array( 'id' => 1, 'name' => '', 'cat_name' => 'Food & Beverage', 'quantity' => 1,
'price' => 25, 'image' => 'books_image/calories_fat_carbohydrate.png' ),
array( 'id' => 2, 'name' => '', 'cat_name' => 'Food & Beverage', 'quantity' => 5,
'price' => 38, 'image' => 'books_image/the_law_relating_to_food.png' ),
array( 'id' => 3, 'name' => '', 'cat_name' => 'Food & Beverage', 'quantity' => 5,
'price' => 19, 'image' => 'books_image/it_starts_with_food.png' ),
array( 'id' => 3, 'name' => '', 'cat_name' => 'Food & Beverage', 'quantity' => 2,
'price' => 19, 'image' => 'books_image/it_starts_with_food.png' ),
array( 'id' => 1, 'name' => '', 'cat_name' => 'Food & Beverage', 'quantity' => 1,
'price' => 25, 'image' => 'books_image/calories_fat_carbohydrate.png' ),
array( 'id' => 2, 'name' => '', 'cat_name' => 'Food & Beverage', 'quantity' => 5,
'price' => 38, 'image' => 'books_image/the_law_relating_to_food.png' )
);
// SORT ARRAY OF ARRAYS FIRST
usort($arrays, 'sort_ids');
// MERGE DUPLICATES
$record_number = count($arrays);
for ($i=0; $i<$record_number; $i++) {
// if this is not the first loop and if this is a duplicate
if(isset($temp_id) && $temp_id == $arrays[$i]['id']) {
// add quantity of the previous array here
$arrays[$i]['quantity'] += $temp_quantity;
// unset previous array
unset($arrays[$i-1]);
}
$temp_id = $arrays[$i]['id'];
$temp_quantity = $arrays[$i]['quantity'];
}
// PRINT ARRAY OF ARRAYS
echo '<pre>';
print_r($arrays);
echo '</pre>';