我该如何将嵌套集模型的数据格式化为数组？

Question

让我们立即着手解决主要问题，我有以下这样的输入

$category = array(
  'A' => array('left' => 1, 'right' => 8),
  'B' => array('left' => 2, 'right' => 3),
  'C' => array('left' => 4, 'right' => 7),
  'D' => array('left' => 5, 'right' => 6),
  'E' => array('left' => 9, 'right' => 10),
);

我希望输出结果类似于这样。

$tree = array(
  array('A', 'B'),
  array('A', 'C', 'D'),
  array('E'),
);

哪个函数是最好和最快的循环遍历输入数组并创建输出结果，如下所示？

- quocnguyen.clgt

---

您所期望的输出并不反映出一个嵌套集合。更应该像array(A => array(B => null, C => array(D => null), E => null)这样。 - Steven Moseley

@Steven Moseley：那个输出结果是让这个函数难以理解的原因。 - quocnguyen.clgt

@StevenMoseley 我的意思是“所需输出”使问题看起来很难，实际上我已经花费了60分钟以上的时间，但没有任何结果。 - quocnguyen.clgt

@StevenMoseley 你的输出对我更有意义，但是使用你的输出打印类别面包屑是否容易呢？A > B A > B > C E - quocnguyen.clgt

以下是解决您问题的方案。 - Steven Moseley

Answer 1

使用嵌套集合进行操作是递归的绝佳案例。

假设你有以下数据：

$category = array(
    'A' => array('left' => 1, 'right' => 9),
    'B' => array('left' => 2, 'right' => 4),
    'C' => array('left' => 5, 'right' => 8),
    'D' => array('left' => 6, 'right' => 7),
    'E' => array('left' => 10, 'right' => 11),
);

以下内容将把您的嵌套集数据转换为符合PHP标准的嵌套数组:

function createTree($category, $left = 0, $right = null) {
    $tree = array();
    foreach ($category as $cat => $range) {
        if ($range['left'] == $left + 1 && (is_null($right) || $range['right'] < $right)) {
            $tree[$cat] = createTree($category, $range['left'], $range['right']);
            $left = $range['right'];
        }
    }
    return $tree;
}

$tree = createTree($category);
print_r($tree);

输出：

Array
(
    [A] => Array
        (
            [B] => Array
                (
                )

            [C] => Array
                (
                    [D] => Array
                        (
                        )

                )

        )

    [E] => Array
        (
        )

)

接着您可以用以下方式将您的树状结构转换为所需的格式：

function flattenTree($tree, $parent_tree = array()) {
    $out = array();
    foreach ($tree as $key => $children) {
        $new_tree = $parent_tree;
        $new_tree[] = $key;
        if (count($children)) {
             $child_trees = flattenTree($children, $new_tree);
            foreach ($child_trees as $tree) {
                $out[] = $tree;
            }
        } else {
            $out[] = $new_tree;
        }
    }
    return $out;
}

$tree = flattenTree($tree);
print_r($tree);

输出结果：

Array
(
    [0] => Array
        (
            [0] => A
            [1] => B
        )

    [1] => Array
        (
            [0] => A
            [1] => C
            [2] => D
        )

    [2] => Array
        (
            [0] => E
        )

)

- Steven Moseley

Answer 2

另一种解决方案，无需递归（请进行测试）

$result = array();

    foreach($category as $key => $value) {

        /*Get current row index*/
        $i = count($result);

        if($i == 0) {
            $result[] = array($key);
        } else {

            $iParent = -1;

            /*Find parent index*/
            for($j = count($result[$i-1]) - 1; $j >= 0; $j--) {
                if($value['left'] > $category[$result[$i-1][$j]]['left'] 
                    && $value['right'] < $category[$result[$i-1][$j]]['right']) {
                    $iParent = $j;
                    break;
                }
            }

            if($iParent == -1) { $result[] = array($key);}

            if($iParent == count($result[$i-1]) - 1) {
                // append to last
                $result[$i-1][] = $key;
            } else {
                // make new list
                $result[$i] = array_slice($result[$i-1], 0, $iParent + 1);
                $result[$i][] = $key;
            }
        }
    }

    print_r($result);

- thanh.dang

Answer 3

上述函数存在一个错误。@tree第二个数组的顶级类别被删除了。以下是修复方法：

foreach ($category as $name => $range) {
    $line[$range['left']] = $name;
    $line[$range['right']] = $name;
}

ksort($line);
$tree = array();
$count = 0;

foreach ($line as $name) {
    if (!isset($open[$name])) {
        $open[$name] = true;
        $count++;
    }
    else {
        if ($count > 0) {
            $count = 0;
            $tree[] = array_keys($open);
        }
        unset($open[$name]);
    }
}

- Andy Nghi

Answer 4

我稍微修改了Stiven的代码。

public function createTree($category, $left = 0, $right = null) {
    $tree = array();
    foreach ($category as $cat => $range) {
        if ($range['clf'] == $left + 1 && (is_null($right) || $range['crt'] < $right)) {
            $tree[$cat]= array();
            $tree[$cat]['title']=$range['title'];
            if($range['crt']-$range['clf']>1){
                $tree[$cat]['sub'] = $this->createTree($category, $range['clf'], $range['crt']);
            }
            $left = $range['crt'];
        }
    }
    return $tree;
}

- user3500854

Answer 5

如果你不想使用递归：

foreach ($category as $name => $range) {
    $line[$range['left']] = $name;
    $line[$range['right']] = $name;
}

ksort($line);
$count = 0;

foreach($line as $name) {
    if ( ! isset($open[$name])) {
        $open[$name] = true;
        $result[$name] = true;
        $count++;
    } else {
        unset($open[$name]);
        if ($count > 0) {
            $count = 0;
            $tree[] = array_keys($result);
            $result = $open;
        } else {
            $result = array();
        }
    }
}

- quocnguyen

---

递归是处理潜在无限嵌套层次的必要手段。你测试过这个吗？ - Steven Moseley