如何从含公共值的数组列表构建符合层级的嵌套数组？

给定层级结构：

group
  |__unit
       |__department
                |__team

能否从一组分散的关联数组生成匹配上述层级的嵌套数组？

示例输入 #

[
   ["group" => "group2"],
   ["group" => "group2", "unit" => "unit11", "department" => "department50", "team" => "team10"],
   ["group" => "group2", "unit" => "unit11", "department" => "department50", "team" => "team58"],
   ["group" => "group2", "unit" => "unit10"],
   ["group" => "group5", "unit" => "unit23"],
   ["group" => "group5", "unit" => "unit23", "department" => "department101"]
]

期望输出 #

[
    "group2" => [
        "unit11" => [
            "department50" => [
                ["team10"],
                ["team58"]                
             ],
        ],    
        "unit10" => [],
    ],

    "group5" => [
        "unit23" => [
            "department101" => []                
        ],
    ],    
]

解决方案 #

可以通过按层级顺序遍历构建的方式实现，核心思路是沿着group -> unit -> department -> team的层级路径，逐个输入项逐层创建嵌套节点，最后一层单独处理元素添加。

PHP 实现代码 #

<?php
$input = [
    ["group" => "group2"],
    ["group" => "group2", "unit" => "unit11", "department" => "department50", "team" => "team10"],
    ["group" => "group2", "unit" => "unit11", "department" => "department50", "team" => "team58"],
    ["group" => "group2", "unit" => "unit10"],
    ["group" => "group5", "unit" => "unit23"],
    ["group" => "group5", "unit" => "unit23", "department" => "department101"]
];

$output = [];
// 定义固定层级顺序
$hierarchy = ['group', 'unit', 'department', 'team'];

foreach ($input as $item) {
    $current = &$output;
    $levelIndex = 0;

    foreach ($hierarchy as $level) {
        // 当前输入项没有该层级的键，停止向下构建
        if (!isset($item[$level])) {
            break;
        }
        $value = $item[$level];
        $levelIndex++;

        // 处理最后一层team，直接添加为子元素
        if ($level === 'team') {
            if (!is_array($current)) {
                $current = [];
            }
            $current[] = [$value];
            break;
        }

        // 非最后一层，确保当前节点存在
        if (!isset($current[$value])) {
            $current[$value] = [];
        }
        // 移动到下一层级的引用
        $current = &$current[$value];
    }

    // 对于不完整的层级（如只有group/unit），保持节点为空数组
    if ($levelIndex < count($hierarchy) && empty($current)) {
        $current = [];
    }
}

print_r($output);
?>

代码说明 #

1. 先定义固定的层级顺序$hierarchy，明确嵌套的先后逻辑
2. 遍历每个输入项，通过引用&$current跟踪当前构建的嵌套位置，避免重复遍历整个结构
3. 逐层检查输入项是否包含当前层级的键，存在则创建或进入对应节点
4. 最后一层team单独处理，直接将其包装为数组添加到对应父节点中
5. 对于不完整的层级（如只有group或unit的输入项），确保对应节点为空数组，符合期望格式

内容的提问来源于stack exchange，提问作者pileup