嵌套數組。第三個層次是消失

Question

我有一個數組：我想

$a = array(
    "7" => array(
     "id" => 7, 
     "parent" => 6 
    ), 
    "6" => array(
     "id" => 6, 
     "parent" => 5 
    ), 
    "5" => array(
     "id" => 5, 
     "parent" => 4 
    ), 
    "4" => array(
     "id" => 4, 
     "parent" => 0 
    ), 
    "3" => array(
     "id" => 7, 
     "parent" => 2 
    ), 
    "2" => array(
     "id" => 7, 
     "parent" => 1 
    ), 
    "1" => array(
     "id" => 7, 
     "parent" => 0 
    ) 
); 

結果是：

$a = array(
    "4" => array(
     "id" => 4, 
     "parent" => 0, 
     array(
      "5" => array(
       "id" => 5, 
       "parent" => 4, 
       array(
        "6" => array(
         "id" => 6, 
         "parent" => 5, 
         array(
          "7" => array(
           "id" => 7, 
           "parent" => 6 
          ) 
         ) 
        ) 
       ) 
      ) 
     ) 
    ), 
    "2" => array(
     "id" => 7, 
     "parent" => 1, 
     array(
      "3" => array(
       "id" => 7, 
       "parent" => 2 
      ) 
     ) 
    ), 
    "1" => array(
     "id" => 7, 
     "parent" => 0 
    ) 
); 

，我使用的代碼是這樣的：

foreach($a as $v) 
{ 
    if(isset($a[$v['PARENT']])) 
    { 
     $a[$v['PARENT']][$v['ID']] = $v; 
     unset($a[$v['ID']]); 
    } 
} 

和問題是我得到的結果是：

$a = array(
    "4" => array(
     "id" => 4, 
     "parent" => 0, 
     array(
      "5" => array(
       "id" => 5, 
       "parent" => 4 
      ) 
     ) 
    ), 
    "2" => array(
     "id" => 7, 
     "parent" => 1, 
     array(
      "3" => array(
       "id" => 7, 
       "parent" => 2 
      ) 
     ) 
    ), 
    "1" => array(
     "id" => 7, 
     "parent" => 0 
    ) 
); 

而不是它的結果。

Answer 1

解決你的問題，你需要正確地理解如何variable referencing/aliasing in PHP作品。

請看下面的示例代碼，它不看你太大的不同，但利用引用才能訪問，即使它已經「移師」任何父母：

# transform $flat into a tree: 
foreach($flat as $id => &$value) 
{ 
    # check if there is a parent 
    if ($parentId = $value['parent']) 
    { 
     $flat[$parentId][0][$id] =& $value; # add child to parent 
     unset($flat[$id]); # remove reference from topmost level 
    } 
} 
unset($value); # remove iterator reference 
print_r($flat); # your tree 

$flat現在包含所有值從$flat - 但重新排序。 Demo。

Answer 2

你確定輸出數組是正確的嗎？關鍵2肯定是1的孩子（因爲2有'parent'=>1）？如果情況並非如此，我不明白究竟在做什麼以及密鑰如何相互關聯。

如果2應該是1一個孩子，這個工程：

$keep = array(); 
foreach ($a as $k => &$v) { 
    // Loop the array first time and create references to 
    // structure the array how you want it 
    if ($v['parent']) { 
    $a[$v['parent']][0] = array($k => &$v); 
    } else $keep[] = $k; 
} 

foreach ($a as $k => $v) { 
    // Loop it again to get rid of non-root nodes from the root 
    if (!in_array($k,$keep)) { 
    unset($a[$k]); 
    } 
} 

print_r($a);