使用 foreach 循环创建多维数组

我正在尝试使用 foreach 循环在 PHP 中创建一个多维数组.这是目前为止的代码:

$levels = array('low', 'medium', 'high');$attributes = array('fat', 'quantity', 'ratio', 'label');foreach ($levels as $key => $level):foreach ($attributes as $k =>$attribute):$variables[] = $attribute .'_' .$级别;Endforeach;Endforeach;echo '
'.print_r($levels,1) .'</pre>';echo '
'.print_r($variables,1) .'</pre>';
这段代码的输出是一个一维数组；然而，这不是本意.所需的数组应如下所示:
应该如何修改代码才能达到目标?
 解决方案 
您就快到了.只需将级别添加到数组创建中:)
$levels = array('low', 'medium', 'high');$attributes = array('fat', 'quantity', 'ratio', 'label');foreach ($levels as $key => $level):foreach ($attributes as $k =>$attribute):$variables[$level][] = $attribute .'_' .$级别;//将 $variables[] 改为 $variables[$level][]Endforeach;Endforeach;echo '
'.print_r($levels,1) .'</pre>';echo '
'.print_r($variables,1) .'</pre>';
输出
数组([低] =>大批([0] =>脂肪_低[1] =>数量_低[2] =>比率_低[3] =>标签低)[中] =>大批([0] =>肥中[1] =>数量_中等[2] =>比率_中[3] =>label_medium)[高] =>大批([0] =>脂肪高[1] =>数量_高[2] =>比率_高[3] =>标签高))
I am trying to create a multidimensional array in PHP using a foreach loop.  Here is the code thus far:
$levels = array('low', 'medium', 'high');
$attributes = array('fat', 'quantity', 'ratio', 'label');

foreach ($levels as $key => $level):
       foreach ($attributes as $k =>$attribute):
             $variables[] = $attribute . '_' . $level;
       endforeach;
endforeach;

echo '<pre>' . print_r($levels,1) . '</pre>';   
echo '<pre>' . print_r($variables,1) . '</pre>';    
The output from this code is a single dimension array; however, that is not the intent.  The desired array should look like this:



How should the code be modified to achieve the goal?
 解决方案 
You're aaalmost there. Just add the level to the array creation :)
$levels = array('low', 'medium', 'high');
$attributes = array('fat', 'quantity', 'ratio', 'label');

foreach ($levels as $key => $level):
       foreach ($attributes as $k =>$attribute):
             $variables[$level][] = $attribute . '_' . $level; // changed $variables[] to $variables[$level][]
       endforeach;
endforeach;

echo '<pre>' . print_r($levels,1) . '</pre>';   
echo '<pre>' . print_r($variables,1) . '</pre>';  
Output
Array
(
    [low] => Array
        (
            [0] => fat_low
            [1] => quantity_low
            [2] => ratio_low
            [3] => label_low
        )

    [medium] => Array
        (
            [0] => fat_medium
            [1] => quantity_medium
            [2] => ratio_medium
            [3] => label_medium
        )

    [high] => Array
        (
            [0] => fat_high
            [1] => quantity_high
            [2] => ratio_high
            [3] => label_high
        )

)