php - 如何在 PHP 中将单个数组转换为多维数组？

Question

所以我有一个看起来像这样的数组：

[98] => Array
(
    [City] => Caracas
    [Country] => Venezuela
    [Continent] => Latin America
)

[99] => Array
(
    [City] => Cairo
    [Country] => Egypt
    [Continent] => Middle East
)

[105] => Array
(
    [City] => Abu Dhabi
    [Country] => United Arab Emirates
    [Continent] => Middle East
)

[106] => Array
(
    [City] => Dubai
    [Country] => United Arab Emirates
    [Continent] => Middle East
)

[107] => Array
(
    [City] => Montreal
    [Country] => Canada
    [Continent] => North America
)

我正在尝试将此数组排序为多维数组，以便它输出如下内容：

Continent
    - Country Name    
      -- Cities under Every Country

我正在使用 PHP。谁能指出我应该如何去做的一个好的起点？

Answer 1

$array = array(
    98 => array(
        'City' => 'Caracas',
        'Country' => 'Venezuela',
        'Continent' => 'Latin America',
    ),
    99 => array(
        'City' => 'Cairo',
        'Country' => 'Egypt',
        'Continent' => 'Middle East',
    ),
    105 => array(
        'City' => 'Abu Dhabi',
        'Country' => 'United Arab Emirates',
        'Continent' => 'Middle East',
    ),
    106 => array(
        'City' => 'Dubai',
        'Country' => 'United Arab Emirates',
        'Continent' => 'Middle East',
    ),
    107 => array(
        'City' => 'Montreal',
        'Country' => 'Canada',
        'Continent' => 'North America',
    )
);

$newArray = array();
foreach ($array as $row)
{
   $newArray[$row['Continent']][$row['Country']][] = $row['City'];
}

print_r($newArray);

Answer 2

我认为你只需要循环你的数组并使用一些值作为键和其他一些值作为值创建一个新的，例如

$new_array = array();
foreach($array as $val)
{ 
     $new_array[$val['Continent']][$val['Country']] = array('City' => $val['City']);
}  

现场样品

Answer 3

这个解决方案怎么样：

function arrayToMultiDimensionalArray(array $elements, array $dimensions)
{
    $output = [];

    foreach ($elements as $element) {
        $outputElement =& $output;

        foreach ($dimensions as $dimension) {
            $outputElement =& $outputElement[$element[$dimension]];
        }

        $outputElement[] = $element;
    }

    return $output;
}

$dimensions = ['Continent', 'Country'];

$tree = arrayToMultiDimensionalArray($array, $dimensions);