我有一個問題已經困擾我好幾周了，我找不到不涉及遞回的干凈解決方案。
這就是問題所在：采用嵌套關聯陣列的平面陣列并將其分組為一個深度嵌套的物件。此物件的頂層將其父屬性為空。
這是我的解決方案，但我承認它遠非完美。我相當肯定這可以在沒有任何遞回的情況下在一個回圈中完成，但是對于我的一生，我無法解決！
//Example single fork
$data = array(
//Top of Tree
0 => array(
"name" => "A",
"parent" => null,
"id" => 1,
),
//B Branch
1 => array(
"name" => "B",
"parent" => "1",
"id" => 2,
),
2 => array(
"name" => "B1",
"parent" => "2",
"id" => 3,
),
3 => array(
"name" => "B2",
"parent" => "3",
"id" => 4,
),
4 => array(
"name" => "B3",
"parent" => "4",
"id" => 5,
),
//C Branch
5 => array(
"name" => "C",
"parent" => "1",
"id" => 6,
),
6 => array(
"name" => "C1",
"parent" => "6",
"id" => 7,
),
7 => array(
"name" => "C2",
"parent" => "7",
"id" => 8,
),
8 => array(
"name" => "C3",
"parent" => "8",
"id" => 9,
),
);
Actual anonymised example
array:7214 [▼
0 => array:3 [▼
"name" => ""
"parent" => null
"id" =>
]
1 => array:3 [▼
"name" => ""
"parent" =>
"id" =>
]
2 => array:3 [▼
"name" => ""
"parent" =>
"id" =>
]
3 => array:3 [▼
"name" => ""
"parent" =>
"id" =>
]
4 => array:3 [▼
"name" => ""
"parent" =>
"id" =>
]
5 => array:3 [▼
"name" => ""
"parent" =>
"id" =>
]
6 => array:3 [▼
"name" => ""
"parent" =>
"id" =>
]
7 => array:3 [▼
"name" => ""
"parent" =>
"id" =>
]
8 => array:3 [▼
"name" => ""
"parent" =>
"id" =>
]
9 => array:3 [▼
"name" => ""
"parent" =>
"id" =>
]
10 => array:3 [▼
"name" => ""
"parent" =>
"id" =>
]
Another example deeper nesting
{
"name":"top",
"id":xxx,
"children":{
"second":{
"name":"second",
"id":xxx,
"children":{
"Third":{
"name":"third",
"id":xxx,
"children":{
"fourth":{
"name":"fourth",
"id":xxx
}
}
}
}
}
}
}
$originalLength = count($data);
$obj = [];
while ($originalLength > 0) {
foreach ($data as $item) {
$name = $item['name'];
$parent = $item['parent'];
$a = isset($obj[$name]) ? $obj[$name] : array('name' => $name, 'id'=>$item['id']);
if (($parent)) {
$path = get_nested_path($parent, $obj, array(['']));
try {
insertItem($obj, $path, $a);
} catch (Exception $e) {
continue;
//echo 'Caught exception: ', $e->getMessage(), "\n";
}
}
$obj[$name] = isset($obj[$name]) ? $obj[$name] : $a;
$originalLength--;
}
}
echo json_encode($obj['A']);
function get_nested_path($parent, $array, $id_path)
{
if (is_array($array) && count($array) > 0) {
foreach ($array as $key => $value) {
$temp_path = $id_path;
array_push($temp_path, $key);
if ($key == "id" && $value == $parent) {
array_shift($temp_path);
array_pop($temp_path);
return $temp_path;
}
if (is_array($value) && count($value) > 0) {
$res_path = get_nested_path(
$parent, $value, $temp_path);
if ($res_path != null) {
return $res_path;
}
}
}
}
return null;
}
function insertItem(&$array, $path, $toInsert)
{
$target = &$array;
foreach ($path as $key) {
if (array_key_exists($key, $target))
$target = &$target[$key];
else throw new Exception('Undefined path: ["' . implode('","', $path) . '"]');
}
$target['children'] = isset($target['children']) ? $target['children'] : [];
$target['children'][$toInsert['name']] = $toInsert;
return $target;
}
uj5u.com熱心網友回復：
這是我對我認為是所需輸出的看法：
function buildTree(array $items): ?array {
// Get a mapping of each item by ID, and pre-prepare the "children" property.
$idMap = [];
foreach ($items as $item) {
$idMap[$item['id']] = $item;
$idMap[$item['id']]['children'] = [];
}
// Store a reference to the treetop if we come across it.
$treeTop = null;
// Map items to their parents' children array.
foreach ($idMap as $id => $item) {
if ($item['parent'] && isset($idMap[intval($item['parent'])])) {
$parent = &$idMap[intval($item['parent'])];
$parent['children'][] = &$idMap[$id];
} else if ($item['parent'] === null) {
$treeTop = &$idMap[$id];
}
}
return $treeTop;
}
這會執行兩個陣列回圈，一個按 ID 映射資料，然后一個將子級分配給父級。需要注意的一些關鍵要素：
- 第一個回圈中的構建
$idMap也有效地復制了此處的專案，因此我們不會影響原始輸入陣列（除非它已經包含參考）。 - 在第二個回圈中，使用了
&對其他專案的參考，否則默認情況下 PHP 會在賦值時有效地創建一個副本，因為這些是陣列（并且 PHP 在賦值時復制陣列，這與 PHP 中的物件或其他一些語言（如 JavaScript）中的陣列不同）。這使我們能夠在整個結構中有效地共享相同的陣列“項”。 - 這不能防止錯誤輸入。輸入資料中的無效映射或回圈參考可能會導致問題，盡管我們的函式應該始終只執行兩個回圈，因此至少不應該陷入無限/窮舉回圈。
轉載請註明出處，本文鏈接：https://www.uj5u.com/net/515759.html
標籤：php递归嵌套的引用传递