无限极分类，把子集数组压到父集数组的一个子项下面，用于在前台模板更好的循环显示

static public function unlimitedForLayer($data,$pid=0){
$arr=array();
foreach ($data as $v) {
if ($v['pid']==$pid) {
$v['child']=self::unlimitedForLayer($data,$v['id']);
$arr[]=$v;
}
}
return $arr;
}

<?php
namespace Home\Controller;
use Think\Controller;
use Home\Clas\Cate;
class IndexController extends Controller {
public function index(){
$data=array(
'0'=>array(
'id'=>1,
'pid'=>0
),
'1'=>array(
'id'=>2,
'pid'=>0
),
'2'=>array(
'id'=>3,
'pid'=>1
),
'3'=>array(
'id'=>4,
'pid'=>3
)
);
//$data=Cate::unlimitedForLevel($data);
$data=Cate::unlimitedForLayer($data);
echo '<pre>';
print_r($data);die;
echo '</pre>';
$this->display();
}
}