PHP - 배열 목록에서 배열 트리 형태로 구현하기

일반 배열을 카테고리 및 하위 카테고리 형태로 구현한 소스입니다.

<?php
 $list = array(
        array('idx' => 1,  'parent_id' => 0),
        array('idx' => 2,  'parent_id' => 0),
        array('idx' => 3,  'parent_id' => 0),
        array('idx' => 4,  'parent_id' => 0),
        array('idx' => 5,  'parent_id' => 0),
        array('idx' => 6,  'parent_id' => 2),
        array('idx' => 7,  'parent_id' => 2),
        array('idx' => 8,  'parent_id' => 3),
        array('idx' => 9,  'parent_id' => 4),
        array('idx' => 10, 'parent_id' => 9)
 );

 $tree = Tree_Array($list, 'idx', 'parent_id');
 print_r($tree);


 function Tree_Array($atr, $id='id', $parent_id='parent', $children='children')
 {
    $nlist = array(
        array( $children => array() )
    );
    $raw = array(&$nlist[0]);
    if(isset($atr))
    {
        foreach($atr as $q => $w)
        {
            $raw[$w[$parent_id]][$children][$w[$id]] = $w;
            $raw[$w[$id]] = &$raw[$w[$parent_id]][$children][$w[$id]];
        }
    }

    return $nlist[0][$children];
 }

 /*
 결과:
 Array
 (
    [1] => Array
        (
            [idx] => 1
            [parent_id] => 0
        )
    [2] => Array
        (
            [idx] => 2
            [parent_id] => 0
            [children] => Array
                (
                    [6] => Array
                        (
                            [idx] => 6
                            [parent_id] => 2
                        )
                    [7] => Array
                        (
                            [idx] => 7
                            [parent_id] => 2
                        )
                )
        )
    [3] => Array
        (
            [idx] => 3
            [parent_id] => 0
            [children] => Array
                (
                    [8] => Array
                        (
                            [idx] => 8
                            [parent_id] => 3
                        )
                )
        )
    [4] => Array
        (
            [idx] => 4
            [parent_id] => 0
            [children] => Array
                (
                    [9] => Array
                        (
                            [idx] => 9
                            [parent_id] => 4
                            [children] => Array
                                (
                                    [10] => Array
                                        (
                                            [idx] => 10
                                            [parent_id] => 9
                                        )
                                )
                        )
                )
        )
    [5] => Array
        (
            [idx] => 5
            [parent_id] => 0
        )
 )
 */
 ?>