如何从另一个数组中获取树状数组？

Question

With a table on my database that stores items of a menu, where every item has an ID, a NAME, and a FATHER ID, I need to arrange it and get a tree-like structure of multiple levels. What I need is an array with the top level menus, then every element with his 'childs' array that contains the sub menus, and this sub menus with their 'childs' array containing their respective sub sub menus an so for. English is no my native language so bear with me :)

An example for better understanding.

I have the following menu in array form:

1- System
  2- Profile
  3- Account
    4- Info
    5- Security
6- Logout

With the following array:

$array = array(
   array('id' => 1, 'item'=>'System', 'id_father' => null),
   array('id' => 2, 'item'=>'Profile', 'id_father' => 1),
   array('id' => 3, 'item'=>'Account', 'id_father' => 2),
   array('id' => 4, 'item'=>'Info', 'id_father' => 3),
   array('id' => 5, 'item'=>'Security', 'id_father' => 3),
   array('id' => 6, 'item'=>'Logout', 'id_father' => 1)
);

How can I get the following ? :

array(
  array('id' => 1, 'item'=>'System', 'id_father' => null,
     'childs' => array(
         array('id' => 2, 'item'=>'Profile', 'id_father' => 1),
         array('id' => 3, 'item'=>'Account', 'id_father' => 2,
           'childs' => array(
              array('id' => 4, 'item'=>'Info', 'id_father' => 3),
              array('id' => 5, 'item'=>'Security', 'id_father' => 3)
           ),
         ),
      ),
  ),
  array('id' => 6, 'item'=>'Logout', 'id_father' => 1)
);

Answer 1

Change $array to :

$array = array(
 array('id' => 1, 'item'=>'System', 'id_father' => null),
 array('id' => 2, 'item'=>'Profile', 'id_father' => 1),
 array('id' => 3, 'item'=>'Account', 'id_father' => 1), // set id_father = 1
 array('id' => 4, 'item'=>'Info', 'id_father' => 3),
 array('id' => 5, 'item'=>'Security', 'id_father' => 3),
 array('id' => 6, 'item'=>'Logout', 'id_father' => null) // edited to set id_father = null
);

Do it:

function tree( $ar, $pid = null ) {
$op = array();
foreach( $ar as $item ) {
    if( $item['id_father'] == $pid ) {
        $op[$item['id']] = array(
            'item' => $item['item'],
            'id_father' => $item['id_father'],
            'id' => $item['id']
        );
        // using recursion
        $children =  tree( $ar, $item['id'] );
        if( $children ) {
            $op[$item['id']]['childs'] = $children;
        }
    }
 }
 return $op;
}


$tree = tree($array);

echo '<pre>';
print_r( $tree);
echo '</pre>';

// OUTPUT

Array
(
 [1] => Array
    (
        [item] => System
        [id_father] => 
        [id] => 1
        [childs] => Array
            (
                [2] => Array
                    (
                        [item] => Profile
                        [id_father] => 1
                        [id] => 2
                    )

                [3] => Array
                    (
                        [item] => Account
                        [id_father] => 1
                        [id] => 3
                        [childs] => Array
                            (
                                [4] => Array
                                    (
                                        [item] => Info
                                        [id_father] => 3
                                        [id] => 4
                                    )

                                [5] => Array
                                    (
                                        [item] => Security
                                        [id_father] => 3
                                        [id] => 5
                                    )

                            )

                    )

            )

    )

[6] => Array
    (
        [item] => Logout
        [id_father] => 
        [id] => 6
    )

)

Answer 2

There is no need to recursion in this way :

$pool = array();
foreach ($array as $value) {
    $pool[$value['id']] = $value;
    $pool[$value['id']]['children'] = array();
}
foreach ($pool as $k => $v) {
    if ($v['id_father']) {
        $pool[$v['id_father']]['children'][] = &$pool[$k];
    }
    else
        $parent[] = $v['id'];
}
$result = array();
foreach ($parent as $val) {
    $result = $result + $pool[$val];
}
print_r($result);