无限级分类是开发中常见的情况了,在这里我收藏了下并整理了下常见的无限极分类算法总结归纳.
['id'=>1,'name'=>'家居','father'=>NULL], 2=>['id'=>2,'name'=>'服装','father'=>NULL], 3=>['id'=>3,'name'=>'护肤品','father'=>NULL], 4=>['id'=>4,'name'=>'生活日用','father'=>1], 5=>['id'=>5,'name'=>'家庭装修','father'=>1], 6=>['id'=>6,'name'=>'厨房卫浴','father'=>1], 7=>['id'=>7,'name'=>'男装','father'=>2], 8=>['id'=>8,'name'=>'女装','father'=>2], 9=>['id'=>9,'name'=>'面部护肤','father'=>3], 10=>['id'=>10,'name'=>'补水保湿','father'=>9], 11=>['id'=>11,'name'=>'收纳用品','father'=>4], 12=>['id'=>12,'name'=>'牛仔裤','father'=>7],];function generateTree($items){ $tree = array(); foreach($items as $item){ if(isset($items[$item['father']])){ $items[$item['father']]['son'][] = &$items[$item['id']]; }else{ $tree[] = &$items[$item['id']]; } } return $tree;}$tree = generateTree($arr);print_r($tree);?> 输出：
Array( [0] => Array ( [id] => 1 [name] => 家居 [father] => [son] => Array ( [0] => Array ( [id] => 4 [name] => 生活日用 [father] => 1 [son] => Array ( [0] => Array ( [id] => 11 [name] => 收纳用品 [father] => 4 ) ) ) [1] => Array ( [id] => 5 [name] => 家庭装修 [father] => 1 ) [2] => Array ( [id] => 6 [name] => 厨房卫浴 [father] => 1 ) ) ) [1] => Array ( [id] => 2 [name] => 服装 [father] => [son] => Array ( [0] => Array ( [id] => 7 [name] => 男装 [father] => 2 [son] => Array ( [0] => Array ( [id] => 12 [name] => 牛仔裤 [father] => 7 ) ) ) [1] => Array ( [id] => 8 [name] => 女装 [father] => 2 ) ) ) [2] => Array ( [id] => 3 [name] => 护肤品 [father] => [son] => Array ( [0] => Array ( [id] => 9 [name] => 面部护肤 [father] => 3 [son] => Array ( [0] => Array ( [id] => 10 [name] => 补水保湿 [father] => 9 ) ) ) ) ))
分析:
这个算法利用了循环迭代,将线性结构按照父子关系以树形结构输出,算法的关键在于使用了引用.
优点:速度快,效率高.
缺点:数组的key值必须与id值相同,不便于取出数据(使用递归获取数据)
我们再看下递归的实现：
['id'=>1,'name'=>'家居','father'=>NULL], 2=>['id'=>2,'name'=>'服装','father'=>NULL], 3=>['id'=>3,'name'=>'护肤品','father'=>NULL], 4=>['id'=>4,'name'=>'生活日用','father'=>1], 5=>['id'=>5,'name'=>'家庭装修','father'=>1], 6=>['id'=>6,'name'=>'厨房卫浴','father'=>1], 7=>['id'=>7,'name'=>'男装','father'=>2], 8=>['id'=>8,'name'=>'女装','father'=>2], 9=>['id'=>9,'name'=>'面部护肤','father'=>3], 10=>['id'=>10,'name'=>'补水保湿','father'=>9], 11=>['id'=>11,'name'=>'收纳用品','father'=>4], 12=>['id'=>12,'name'=>'牛仔裤','father'=>7],];function generateTree($arr,$id,$step){ static $tree=[]; foreach($arr as $key=>$val) { if($val['father'] == $id) { $flag = str_repeat('└―',$step); $val['name'] = $flag.$val['name']; $tree[] = $val; generateTree($arr , $val['id'] ,$step+1); } } return $tree;}$tree = generateTree($arr,0,0);foreach ($tree as $val){ echo $val['name'].'';}?> 输出：
家居└―生活日用└―└―收纳用品└―家庭装修└―厨房卫浴服装└―男装└―└―牛仔裤└―女装护肤品└―面部护肤└―└―补水保湿
分析:
利用了递归,数组的key值与id值可以不相同,最后以顺序的结构输出数组
优点:方便遍历,查找父子元素
缺点:php不擅长递归,数据量大的情况下效率会显著降低
总结：两种方法各有利弊，后者不适合大数据下使用，前者推荐吧