PHP实现根据数组的值进行分组的方法

$_array = array(
    array(1,11,'2016-05-18'),
    array(2,11,'2016-05-18'),
    array(3,22,'2016-05-18'),
    array(4,22,'2016-05-18'),
    array(5,33,'2016-05-19'),
    array(6,33,'2016-05-19'),
    array(7,44,'2016-05-19'),
    array(8,44,'2016-05-19'),
    array(9,55,'2016-05-20'),
    array(10,55,'2016-05-20'),
);
var_dump(array_val_chunk($_array));
function array_val_chunk($array){
    $result = array();
    foreach ($array as $key => $value) {
      $result[$value[1].$value[2]][] = $value;
    }
    $ret = array();
    //这里把键值转成了数字的，方便同意处理
    foreach ($result as $key => $value) {
      array_push($ret, $value);
    }
    return $ret;
}