php 无限分类 树形数据格式化代码

　　我们知道很多开源软件的无限分类都是采用递归的算法，但是我们知道递归即浪费时间，又浪费空间（内存），
上次我也分享了个我自己原创的无限分类生成树的方法，一热心php高手网友给我提出了宝贵的建议，我测试了一下，这段代码的时间非常之短参考： ，我再次整理了一下，发现数据库查询出数据之后，我们就已经定好了键值，因而实践中，我们一般会在model中查询出格式化成主键值对应数据的形式，因而我们可以直接用这样的数据，就少了一层循环。代码也非常简洁。

　　原来的代码：

　　 function genTree($items,$id=id,$pid=pid,$son = children){ $tree = array(); //格式化的树 $tmpMap = array(); //临时扁平数据 foreach ($items as $item) { $tmpMap[$item[$id]] = $item; } foreach ($items as $item) { if (isset($tmpMap[$item[$pid]])) { $tmpMap[$item[$pid]][$son][] = &$tmpMap[$item[$id]]; } else { $tree[] = &$tmpMap[$item[$id]]; } } unset($tmpMap); return $tree; } $items1 = array( array(id => 1, pid => 0, name => 一级11 ), array(id => 11, pid => 0, name => 一级12 ), array(id => 2, pid => 1, name => 二级21 ), array(id => 10, pid => 11, name => 二级22 ), array(id => 3, pid => 1, name => 二级23 ), array(id => 12, pid => 11, name => 二级24 ), array(id => 9, pid => 1, name => 二级25 ), array(id => 14, pid => 1, name => 二级26 ), array(id => 4, pid => 9, name => 三级31 ), array(id => 6, pid => 9, name => 三级32 ), array(id => 7, pid => 4, name => 四级41 ), array(id => 8, pid => 4, name => 四级42 ), array(id => 5, pid => 4, name => 四级43 ), array(id => 13, pid => 4, name => 四级44 ), array(id => 15, pid => 8, name => 五级51 ), array(id => 16, pid => 8, name => 五级52 ), array(id => 17, pid => 8, name => 五级53 ), array(id => 18, pid => 16, name => 六级64 ), ); var_dump(genTree($items1));

　　以下是补充：

　　 /** * 此方法由@Tonton 提供 * /** * 将数据格式化成树形结构 * @author Xuefen.Tong * @param array $items * @return array */ function genTree9($items) { $tree = array(); //格式化好的树 foreach ($items as $item) if (isset($items[$item[pid]])) $items[$item[pid]][son][] = &$items[$item[id]]; else $tree[] = &$items[$item[id]]; return $tree; } $items = array( 1 => array(id => 1, pid => 0, name => 江西省), 2 => array(id => 2, pid => 0, name => 黑龙江省), 3 => array(id => 3, pid => 1, name => 南昌市), 4 => array(id => 4, pid => 2, name => 哈尔滨市), 5 => array(id => 5, pid => 2, name => 鸡西市), 6 => array(id => 6, pid => 4, name => 香坊区), 7 => array(id => 7, pid => 4, name => 南岗区), 8 => array(id => 8, pid => 6, name => 和兴路), 9 => array(id => 9, pid => 7, name => 西大直街), 10 => array(id => 10, pid => 8, name => 东北林业大学), 11 => array(id => 11, pid => 9, name => 哈尔滨工业大学), 12 => array(id => 12, pid => 8, name => 哈尔滨师范大学), 13 => array(id => 13, pid => 1, name => 赣州市), 14 => array(id => 14, pid => 13, name => 赣县), 15 => array(id => 15, pid => 13, name => 于都县), 16 => array(id => 16, pid => 14, name => 茅店镇), 17 => array(id => 17, pid => 14, name => 大田乡), 18 => array(id => 18, pid => 16, name => 义源村), 19 => array(id => 19, pid => 16, name => 上坝村), ); print_r(genTree5($items)); print_r(genTree9($items)); //后者输出格式，前者类似，只是数组键值不一样，不过不影响数据结构 /* Array ( [0] => Array ( [id] => 1 [pid] => 0 [name] => 江西省 [son] => Array ( [0] => Array ( [id] => 3 [pid] => 1 [name] => 南昌市 ) [1] => Array ( [id] => 13 [pid] => 1 [name] => 赣州市 [son] => Array ( [0] => Array ( [id] => 14 [pid] => 13 [name] => 赣县 [son] => Array ( [0] => Array ( [id] => 16 [pid] => 14 [name] => 茅店镇 [son] => Array ( [0] => Array ( [id] => 18 [pid] => 16 [name] => 义源村 ) [1] => Array ( [id] => 19 [pid] => 16 [name] => 上坝村 ) ) ) [1] => Array ( [id] => 17 [pid] => 14 [name] => 大田乡 ) ) ) [1] => Array ( [id] => 15 [pid] => 13 [name] => 于都县 ) ) ) ) ) [1] => Array ( [id] => 2 [pid] => 0 [name] => 黑龙江省 [son] => Array ( [0] => Array ( [id] => 4 [pid] => 2 [name] => 哈尔滨市 [son] => Array ( [0] => Array ( [id] => 6 [pid] => 4 [name] => 香坊区 [son] => Array ( [0] => Array ( [id] => 8 [pid] => 6 [name] => 和兴路 [son] => Array ( [0] => Array ( [id] => 10 [pid] => 8 [name] => 东北林业大学 ) [1] => Array ( [id] => 12 [pid] => 8 [name] => 哈尔滨师范大学 ) ) ) ) ) [1] => Array ( [id] => 7 [pid] => 4 [name] => 南岗区 [son] => Array ( [0] => Array ( [id] => 9 [pid] => 7 [name] => 西大直街 [son] => Array ( [0] => Array ( [id] => 11 [pid] => 9 [name] => 哈尔滨工业大学 ) ) ) ) ) ) ) [1] => Array ( [id] => 5 [pid] => 2 [name] => 鸡西市 ) ) ) )*/

　　极其简单有效！！！非常受用！