thinkphp随机有关问题

thinkphp随机问题
比如卖出10条新闻，10条新闻做了排序了：1、2、3、4、5、5、5、6、6、7；
当遇到相同排序号时显示随机显示。也就是相同排序号局部随机显示。
这个东西不知道怎么写了；能不能实现？
------解决思路----------------------

$arr = array( <br />array('id' => 1,'name' => 'aaa','uid'=>1), <br />array('id' => 2,'name' => 'bbb','uid'=>2), <br />array('id' => 3,'name' => 'ccc','uid'=>3), <br />array('id' => 4,'name' => 'ddd','uid'=>4), <br />array('id' => 5,'name' => 'ccc','uid'=>4), <br />array('id' => 6,'name' => 'bbb','uid'=>4), <br />array('id' => 7,'name' => 'bbb','uid'=>5), <br />array('id' => 8,'name' => 'fff','uid'=>6), <br />array('id' => 9,'name' => 'ccc','uid'=>7), <br />array('id' => 10,'name' => 'bbb','uid'=>8), <br />array('id' => 11,'name' => 'ddd','uid'=>8), <br />array('id' => 12,'name' => 'eee','uid'=>9), <br />array('id' => 13,'name' => 'fff','uid'=>10), <br />); <br />usort($arr, function($a, $b) {<br />  if($a['uid'] == $b['uid']) return rand(-1, 1);<br />  return $a['uid'] > $b['uid'] ? 1 : -1;<br />  });<br />print_r($arr);