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IlyaDrummer
Asked:2022-06-27 11:30:43 +0000 UTC2022-06-27 11:30:43 +0000 UTC

如何递归构建树？

  • 772

有一个包含数据的数组。

    $tree = [
    0 => [
        ['id' => 1, 'title' => 'Russia', 'type' => 'country', 'parent_id' => 0],
        ['id' => 2, 'title' => 'Usa', 'type' => 'country', 'parent_id' => 0],
    ],
    1 => [
        ['id' => 3, 'title' => 'Khakassia', 'type' => 'region', 'parent_id' => 1],
        ['id' => 4, 'title' => 'Krasnoyarsk krai', 'type' => 'region', 'parent_id' => 1],
        ['id' => 5, 'title' => 'Texas', 'type' => 'region', 'parent_id' => 2],
        ['id' => 6, 'title' => 'California', 'type' => 'region', 'parent_id' => 2],
    ],
    2 => [
        ['id' => 7, 'title' => 'Abakan', 'type' => 'region', 'parent_id' => 3],
        ['id' => 8, 'title' => 'Abaza', 'type' => 'region', 'parent_id' => 3],
        ['id' => 9, 'title' => 'Krasnoyarsk', 'type' => 'region', 'parent_id' => 4],
        ['id' => 10, 'title' => 'Norilsk', 'type' => 'region', 'parent_id' => 4],
        ['id' => 11, 'title' => 'Dallas', 'type' => 'region', 'parent_id' => 5],
        ['id' => 12, 'title' => 'Houston', 'type' => 'region', 'parent_id' => 5],
        ['id' => 13, 'title' => 'Los Angeles', 'type' => 'region', 'parent_id' => 6],
        ['id' => 14, 'title' => 'Sacramento', 'type' => 'region', 'parent_id' => 6],
    ],
];

我不知道如何递归地锐化一棵树。我可以添加元素和嵌套。

Russia
    - Khakassia
        - Abakan
        - Abaza
    - Krasnoyarsk krai
        - Krasnoyarsk
        - Norilsk

Usa
    - Texas
        - Dallas
        - Houston
    - California
        - Los Angeles
        - Sacramento
php

1 个回答

  1. Best Answer
    //Упрощаем дерево, убираем лишнюю вложенность т.к id обеспечивает нам уникальность записи
//По сути все под-массивы из $tree[0], $tree[1], $tree[2] ... вытаскиваем на уровень вверх
function simpleTree( $tree = [] ) {
    $result = [];
    foreach( $tree as $child ) {
        foreach( $child as $c ) {
            $result[] = $c;
        }
    }
    return $result;
}
//Получаем массив содержащий всех детей родителя по его ID
function getTreeChildsByParentId( $tree = [], $pid = 0 ) {
    $result = [];
    foreach( $tree as $child ) {
        if ($child['parent_id'] == $pid ) {
            $result[] = $child;
        }
    }
    return $result;
}
//Строим дерево
function buildTree( $tree, $pid, $prefix = '' ) {
    foreach( getTreeChildsByParentId( $tree, $pid ) as $p ) {
        echo ($prefix != '' ? $prefix.'- ': '').$p['title']."\n";    
        $pfx = $prefix.( count( getTreeChildsByParentId( $tree, $p['id'] ) ) > 0 ? '  ' : '' );
        buildTree( $tree, $p['id'], $pfx );
    }
}

buildTree( simpleTree($tree), 0, '' );

    结果

    Russia                                                                
    - Khakassia
      - Abakan
      - Abaza
    - Krasnoyarsk krai
      - Krasnoyarsk
      - Norilsk
Usa
  - Texas
    - Dallas
    - Houston
  - California
    - Los Angeles
    - Sacramento
    • 1

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