Array
 (
 [1] => Array
 (
 [0] => 1
 [1] => 1
 )
 
 [2] => Array
 (
 [0] => 2
 [1] => 2
 )
 
 [3] => Array
 (
 [0] => 3
 [1] => 3
 [2] => 3
 )
 
 [4] => Array
 (
 [0] => 4
 )
 
 [5] => Array
 (
 [0] => 5
 [1] => 5
 )
 
 [6] => Array
 (
 [0] => 6
 [1] => 6
 )
 
 )

 $list = array(1,2,3,3,4,5,6,6,5,3,2,1);
 $acit = array_unique($list); //数组去重
 $newarray = array();
 $val_nums = array_count_values($list); //计算数值出现几次
 foreach ($acit as $val) {
 for ($i = 0;$i<$val_nums[$val];$i++) {
 $val_array[$i] = $val;
 }
 $newarray[$val] = $val_array;
 unset($val_array);
 }
 unset($list);unset($acit);unset($val_nums);
 echo "<pre>";print_r($newarray);die;