php 二维数组去重合并将相同数量累加

$arr = array(
array(
'user_id' => 100,
'goods_id' => 10,
'number' => 1,
),
array(
'user_id' => 102,
'goods_id' => 10,
'number' => 1,
),
array(
'user_id' => 102,
'goods_id' => 10,
'number' => 1,
),
array(
'user_id' => 102,
'goods_id' => 10,
'number' => 1,
),
);

$result = array();

foreach($arr as $val){
$key = $val['user_id'].'_'.$val['goods_id'];
if(!isset($result[$key])){
$result[$key] = $val;
}else{
$result[$key]['number'] += $val['number'];
}
}

echo '<pre>';
print_r(array_values($result));
echo '</pre>';

Array
(
[0] => Array
(
[user_id] => 100
[goods_id] => 10
[number] => 1
)

[1] => Array
(
[user_id] => 102
[goods_id] => 10
[number] => 3
)

)