PHP 无限极分类

$data = array(
    array('id' => 1, 'pid' => 0, 'name' => '山西省'),
    array('id' => 2, 'pid' => 0, 'name' => '北京市'),
    array('id' => 3, 'pid' => 1, 'name' => '晋中市'),
    array('id' => 4, 'pid' => 2, 'name' => '朝阳区'),
    array('id' => 5, 'pid' => 2, 'name' => '通州区'),
    array('id' => 6, 'pid' => 4, 'name' => '望京'),
    array('id' => 7, 'pid' => 4, 'name' => '酒仙桥'),
    array('id' => 8, 'pid' => 3, 'name' => '打打县'),
    array('id' => 9, 'pid' => 1, 'name' => '武安市'),
    array('id' => 10, 'pid' => 8, 'name' => '萨达乡'),
    array('id' => 11, 'pid' => 10, 'name' => '陈大苏打村'),
    array('id' => 12, 'pid' => 11, 'name' => '石的撒打算村小组'),
);
//print_r($data);
//exit;
function cation($arr,$num=0,$m=1)
{
    $list = [];
    foreach($arr as $k=>$v){
        if($v['pid'] === $num){
            $v['level'] = $m;
            $v['son'] = cation($arr,$v['id'],$m+1);
            $list[] = $v;

        }
    }
    return $list;
}



$list = cation($data);

print_r(json_encode($list));