Code examples for PHP Infinitus classification (recursive and tree)

This article brings you code examples (recursion and trees) of PHP Infinitus classification. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

(1) .Recursive implementation

function getTree($array, $pid =0, $level = 0){
//声明静态数组,避免递归调用时,多次声明导致数组覆盖 
static $list = []; 
foreach ($array as $key => $value){     
//第一次遍历,找到父节点为根节点的节点 也就是pid=0的节点  
if ($value['pid'] == $pid){
//父节点为根节点的节点,级别为0，也就是第一级
$value['level'] = $level;
//把数组放到list中
$list[] = $value;
//把这个节点从数组中移除,减少后续递归消耗           
unset($array[$key]);           
//开始递归,查找父ID为该节点ID的节点,级别则为原级别+1          
getTree($array, $value['id'], $level+1);
        }
    } 
return $list;
}

The result is as shown in the figure:

(2) .Tree structure

function getTree($items,$pid ="pid") {
    $map  = [];
    $tree = []; 
foreach ($items as &$it){ $map[$it['id']] = &$it; }  
//数据的ID名生成新的引用索引树   
foreach ($items as &$at){
        $parent = &$map[$at[$pid]];    
if($parent) {
            $parent['children'][] = &$at;
        }else{
            $tree[] = &$at;
        }
    }
return $tree;
}

The result is as shown:

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