php二维数组去除重合数据

PHP 二维数组 Array
(
[0] => Array
(
[knowledge_id] => 1
[tag_id] => 2
)

[1] => Array
(
[knowledge_id] => 1
[tag_id] => 3
)

)

把他里面量相同的[knowledge_id] => 1合并只留一个？？？？？？

回复讨论(解决方案)

留哪个呢？还是2个 tag_id 都要？

不用只要一个数组[0] => Array
(
[knowledge_id] => 1
[tag_id] => 2
)

设原数组为 $ar, 则

$res = array(); //结果数组foreach($ar as $v) {  if(! isset($res[$v['knowledge_id']])) $res[$v['knowledge_id']] = $v;}$res = array_values($res);