二维数组按某值分组求和

本文以1,2,3,4,5将数据分组,求和

$users = array(
    array('id'=>1,'age'=>'1'),
    array('id'=>2,'age'=>'2'),
    array('id'=>3,'age'=>'3'),
    array('id'=>4,'age'=>'4'),
    array('id'=>5,'age'=>'5'),
    array('id'=>1,'age'=>'1'),
    array('id'=>2,'age'=>'2'),
    array('id'=>3,'age'=>'3'),
    array('id'=>4,'age'=>'4'),
    array('id'=>5,'age'=>'5'),
    array('id'=>1,'age'=>'1'),
    array('id'=>2,'age'=>'2'),
    array('id'=>3,'age'=>'3'),
    array('id'=>4,'age'=>'4'),
    array('id'=>5,'age'=>'5'),
);

$newArr = [];//存放求和的值
$arr = [];//里面放新数组

foreach ($users as $key => $value) {
        //在新数组就age相加
    if (in_array($value['id'],$arr)) {
        $newArr[$value['id']] += $value['age'];
    } else {
        //不在新数组就将age存入$newArr
        $arr[] = $value['id'];
        $newArr[$value['id']] = $value['age'];
    }
}
echo "<pre>";
print_r($newArr);
结果如下:
/*Array
(
    [1] => 3
    [2] => 6
    [3] => 9
    [4] => 12
    [5] => 15
)*/