怎么取数组的交集，求大神指导

这是两个二维数组$arr,$arr1,怎么取出相同的交集$arr = array(		array("id" => "3","name" => "张三"),		array("id" => "6","name" => "李四"),		array("id" => "8","name" =>  "王五"),		array("id" => "18","name" => "赵六"),	 	array("id" => "20","name" => "七七")	 );$arr1 = array(		array("id" => "6","name" => "张三",),                array("id" => "18","name" => "赵六"),);想要的结果是array(		array("id" => "6","name" => "张三",),                array("id" => "18","name" => "赵六"));

$arr = array(        array("id" => "3","name" => "张三"),        array("id" => "6","name" => "李四"),        array("id" => "8","name" =>  "王五"),        array("id" => "18","name" => "赵六"),        array("id" => "20","name" => "七七")     );$arr1 = array(        array("id" => "6","name" => "张三",),        array("id" => "18","name" => "赵六"),);foreach($arr as $a)  foreach($arr1 as $k=>$b)    if($a == $b) {      $r[] = $b;      unset($arr1[$k]);    }print_r($r);

Array(    [0] => Array        (            [id] => 18            [name] => 赵六        ))

$arr1 = array(        array("id" => "6","name" => "张三",),        array("id" => "18","name" => "赵六"),);