如何递归排序关联数组
我想对以下关联数组进行排序：
$tree = [
"id" => 245974,
"children" => [
[
"id" => 111
],
[
"id" => 245982,
"children" => [
[
"id" => 246093,
"children" => [
[
"id" => 225892
],
[
"id" => 225893
],
[
"id" => 225902
]
]
]
]
]
]
];
在id=>的“搜索值”之后所需的排序顺序225902：
[
"id" => 245974,
"children" => [
[
"id" => 245982, // <-- this is moved up
"children" => [
[
"id" => 246093,
"children" => [
[
"id" => 225902 // <-- this is moved up
],
[
"id" => 225892
],
[
"id" => 225893
]
]
]
]
],
[
"id" => 111
]
]
];
我试过的：
<?php
$category_id = 225902;
function custom_sort(&$a, &$b) {
global $category_id;
if ($a['id'] === $category_id) {
return -1;
}
if ($b['id'] === $category_id) {
return 1;
}
if (array_key_exists('children', $a)) {
if (usort($a['children'], "custom_sort")) {
return -1;
}
}
if (array_key_exists('children', $b)) {
if (usort($b['children'], "custom_sort")) {
return 1;
}
}
return 0;
}
function reorder_tree($tree) {
usort($tree['children'], "custom_sort");
return $tree;
}
echo "<pre>";
var_dump(reorder_tree($tree));
echo "</pre>";
犯罪嫌疑人X1回答
-
幕布斯7119047
伟大的尝试，而且非常在正确的轨道上。比较器中递归的问题在于，usort当数组长度为 1 时不会调用比较器函数，因此是否探索整棵树是usort. 这将放弃id => 245982树的分支。解决方案是避免usort直接在的比较器函数中递归。相反，使用usort根据需要调用的常规递归函数，即当前数组或子数组包含目标 id。我使用一个单独的数组来跟踪哪些元素应该向前移动，但是如果您愿意，您可以跳出循环并将单个元素拼接/取消移动到前面。我们还可以为$category_id函数设置一个参数。这是一种方法：function reorder_tree_r(&$children, $target) { $order = []; $should_sort = false; foreach ($children as $i => &$child) { $order[$i] = false; if (array_key_exists("children", $child) && reorder_tree_r($child["children"], $target) || $child["id"] === $target) { $order[$i] = true; $should_sort = true; } } if ($should_sort) { $priority = []; $non_priority = []; for ($i = 0; $i < count($children); $i++) { if ($order[$i]) { $priority[]= $children[$i]; } else { $non_priority[]= $children[$i]; } } $children = array_merge($priority, $non_priority); } return $should_sort;}function reorder_tree($tree, $target) { if (!$tree || !array_key_exists("children", $tree)) { return $tree; } reorder_tree_r($tree["children"], $target); return $tree;}var_export(reorder_tree($tree, 225902));输出：array ( 'id' => 245974, 'children' => array ( 0 => array ( 'id' => 245982, 'children' => array ( 0 => array ( 'id' => 246093, 'children' => array ( 0 => array ( 'id' => 225902, ), 1 => array ( 'id' => 225892, ), 2 => array ( 'id' => 225893, ), ), ), ), ), 1 => array ( 'id' => 111, ), ),
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