php - 親に応じて配列をソートします。1次元配列の木

Question

それぞれの親の後にすべての子を含む配列を並べ替えるにはどうすればよいですか？1次元配列内にツリーを格納しようとしていると思います。私はusortを使用してこれを理解しようとしましたが、それがその仕事に適したツールではないと思います。

入力配列の例：

array (0 => array ( 'id' => '1', 'parent' => '0', ), 
1 => array ( 'id' => '2', 'parent' => '1', ), 
2 => array ( 'id' => '3', 'parent' => '0', ), 
3 => array ( 'id' => '5', 'parent' => '0', ), 
4 => array ( 'id' => '17', 'parent' => '3', ), 
5 => array ( 'id' => '31', 'parent' => '2', ), 
6 => array ( 'id' => '32', 'parent' => '2', ))

出力例：

Answer 1

実際のツリーを構築することから始めて、そのツリーを平坦化します。

$array = array (0 => array ( 'id' => '1', 'parent' => '0', ),
                1 => array ( 'id' => '2', 'parent' => '1', ),
                2 => array ( 'id' => '3', 'parent' => '0', ),
                3 => array ( 'id' => '5', 'parent' => '0', ),
                4 => array ( 'id' => '17', 'parent' => '3', ),
                5 => array ( 'id' => '31', 'parent' => '2', ),
                6 => array ( 'id' => '32', 'parent' => '2', ));

/* Building a tree. We also save a map of references to avoid                                
   searching the tree for nodes */

//Helper to create nodes                                                                     
$tree_node = function($id, $parent) {
  return array('id' => $id, 'parent' => $parent, 'children' => array());
};

$tree = $tree_node(0, null); //root node                                                     
$map = array(0 => &$tree);
foreach($array as $cur) {
  $id = (int) $cur['id'];
  $parentId = (int) $cur['parent'];
  $map[$id] =& $map[$parentId]['children'][];
  $map[$id] = $tree_node($id, $parentId);
}

//Now recursively flatten the tree:                                                          
function flatter($node) {
  //Create an array element of the node                                            
  $array_element = array('id' => (string) $node['id'],
                         'parent' => (string) $node['parent']);
  //Add all children after me                                                                
  $result = array($array_element);
  foreach($node['children'] as $child) {
    $result = array_merge($result, flatter($child));
  }
  return $result;
}

$array = flatter($tree);
array_shift($array); //Remove the root node, which was only added as a helper                

print_r($array);

Answer 2

<?php

/**
 * @author Prasath A.R
 * @copyright 2012
 * @Date 2012-8-31 17:14
 */

$array = array (0 => array ( 'id' => '1', 'parent' => '0', ),
                1 => array ( 'id' => '2', 'parent' => '1', ),
                2 => array ( 'id' => '3', 'parent' => '0', ),
                3 => array ( 'id' => '5', 'parent' => '0', ),
                4 => array ( 'id' => '17', 'parent' => '3', ),
                5 => array ( 'id' => '31', 'parent' => '2', ),
                6 => array ( 'id' => '32', 'parent' => '2', ));

print_r($array);
echo "<br />";

for($i=0;$i<count($array);$i++)
{
for($j=$i;$j<count($array);$j++)
{
        if($array[$i]['parent']>$array[$j]['parent'])
        {
            $temp=$array[$i];
            $array[$i]=$array[$j];
            $array[$j]=$temp;
        }
    }
}

echo "<h2>After Sorting</h2><br />";
print_r($array);

?>

答えは次のとおりです。

配列 ( [0] => 配列 ( [id] => 1 [親] => 0 )

[1] => Array
    (
        [id] => 2
        [parent] => 1
    )

[2] => Array
    (
        [id] => 3
        [parent] => 0
    )

[3] => Array
    (
        [id] => 5
        [parent] => 0
    )

[4] => Array
    (
        [id] => 17
        [parent] => 3
    )

[5] => Array
    (
        [id] => 31
        [parent] => 2
    )

[6] => Array
    (
        [id] => 32
        [parent] => 2
    )

)

ソート後

配列 ( [0] => 配列 ( [id] => 1 [親] => 0 )

[1] => Array
    (
        [id] => 3
        [parent] => 0
    )

[2] => Array
    (
        [id] => 5
        [parent] => 0
    )

[3] => Array
    (
        [id] => 2
        [parent] => 1
    )

[4] => Array
    (
        [id] => 31
        [parent] => 2
    )

[5] => Array
    (
        [id] => 32
        [parent] => 2
    )

[6] => Array
    (
        [id] => 17
        [parent] => 3
    )

)