递归--无限极分类

/*
 *p1 数据源
 *p2 类型$type=1返回一个二维数组，$type=2返回子孙树
 *p3 初始父id
 *p4 分类等级
 */
function unlimitTree(array $data,$type=1,$pid=0,$level=1)
    {
        if($type == 1){
            static $tree = [];
        }else{
            $tree = [];
        }

        foreach($data as $key => $value) {
            if($value['pid'] == $pid) {
                if($type == 1){
                    $value['level'] = $level;
                    $tree[] = $value;
                    unlimitTree($data,$type,$value['id'],$level+1);
                }else{
                    $value['level'] = $level;
                    $value['children'] = unlimitTree($data,$type,$value['id'],$level+1);
                    $tree[$value['id']] = $value;
                }
            }
        }
        return $tree;
    }

//5行代码非递归实现无限极分类树
function genTree5($items) {
    foreach ($items as $item){
        $items[$item['pid']]['children'][$item['id']] = &$items[$item['id']];
    }
    return $items[0]['children']) ?? [];
}

递归--子孙树转二维数组 可以配合Nestable使用

$json = '[{"id":1,"children":[{"id":2,"children":[{"id":4},{"id":5,"children":[{"id":6},{"id":7},{"id":8}]},{"id":9},{"id":10}]}]},{"id":3},{"id":11},{"id":12}]';

$arr = json_decode($json,true);
$rows = tree_to_row($arr);

function tree_to_row(array $tree,$pid = 0,$childname='children'){
        static $rows = [];
        //简单排序
        $sort = count($tree);
        foreach($tree as $val){
            $rows[] = ['id'=>$val['id'],'pid'=>$pid,'sort'=>$sort];
            $sort--;
            if(isset($val[$childname])){
                tree_to_row($val[$childname],$val['id']);
            }
        }

        return $rows;
}

递归--获取树所有叶子节点

$json = '[{"id":1,"children":[{"id":2,"children":[{"id":4,"children":[{"id":6},{"id":7}]},{"id":5,"children":[{"id":8},{"id":9}]},{"id":10}]}]},{"id":3},{"id":11},{"id":12}]';

$arr = json_decode($json,true);
$rows = all_child_node($arr);

function all_child_node(array $tree,$pre = 0){
        static $rows = [];
        foreach ($tree as $key=>$val){
            $id = $val['id'];
            $children = $val['children'] ?? null;
            if($children){
                $rows[$id] = all_child_node($children,'id'); 
                exo($children,$id);
                if($pre != 0){
                    $rows[$pre] = array_merge($rows[$pre]??[],$rows[$id]);
                }
            }else{
                $rows[$id] = [];
            }
        }
        return $rows;
}

结果1

image.png

结果2

image.png

结果3

image.png