adding items in array

[dadamssg87]

I have an array of products. The array has an ID and price. I'd like to know the most efficient way of adding up all the same ID fields in the array.

 

<?php
$items[] = array(
					'id' => 1,
					'price' => 5.99,
					);
	$items[] = array(
					'id' => 2,
					'price' => 1.99,
					);	
	$items[] = array(
					'id' => 3,
					'price' => 2.40,
					);
	$items[] = array(
					'id' => 2,
					'price' => 6.99,
					);			
	$items[] = array(
					'id' => 4,
					'price' => 8,
					);
	$items[] = array(
					'id' => 2,
					'price' => 3,
					);	
	$items[] = array(
					'id' => 3,
					'price' => 1,
					);

function add_like_items($items)
{
//manipulation

return $sums;
}

//$sums would be an array like 
//$sum[1] = 5.99
//$sum[2] = 11.98
//$sum[3] = 3.40
//$sum[4] = 8 

?>

 

Anybody have suggestions on the best way to go about doing this?

[AbraCadaver]

Not tested:

 

foreach($items as $item) {
   if(isset($sums[$item['id']])) {
      $sums[$item['id']] += $item['price'];
   } else {
      $sums[$item['id']] = $item['price'];
   }
}

[dadamssg87]

works great. Thanks a lot. I would've wrote something way more complicated than need be. I appreciate it!

[xyph]

If you want to go for pure efficiency, I think it would be hard to beat this

 

<?php 

$items[] = array(
'id' => 1,
'price' => 5.99,
);
$items[] = array(
'id' => 2,
'price' => 1.99,
);	
$items[] = array(
'id' => 3,
'price' => 2.40,
);
$items[] = array(
'id' => 2,
'price' => 6.99,
);			
$items[] = array(
'id' => 4,
'price' => 8,
);
$items[] = array(
'id' => 2,
'price' => 3,
);	
$items[] = array(
'id' => 3,
'price' => 1,
);

print_r( subkey_sum($items) );

function subkey_sum( $array ) {

$sum = array();
for( $i=0,$l=count($array); $i<$l; $i++ ) {
	$sum[ $array[$i]['id'] ] = isset($sum[$array[$i]['id']]) ?
		$sum[ $array[$i]['id'] ] + $array[$i]['price'] :
		$array[$i]['price'];
}
return $sum;

}

?>

 

I'm quite sure my method is slightly faster and uses less memory than AbraCadaver's.

 

His is slightly cleaner.

 

You did ask for the most efficient solution though.