PHP-怎么把数组按某一个键值重新组合

Question

下面这个二维数组，怎么按cid重新组合成新的三维数组

$data = array(
    0 =>array(
        'id' => 1,
        'cid'=>1,
        'title' => '标题1'
        ),
    1 =>array(
        'id' => 1,
        'cid'=>1,
        'title' => '标题1'
        ),
    2 =>array(
        'id' => 1,
        'cid'=>2,
        'title' => '标题1'
        ),
    3 =>array(
        'id' => 1,
        'cid'=>2,
        'title' => '标题1'
        )
    )

Answer 1

 $new_data = array();
foreach($data as $key=>$value){
$new_data[$value['cid']][$key]=$value;
}
echo '<pre>';
print_r($new_data);