How to convert a Single Array into a multidimensional array in PHP?

Question

So I have an array that looks like this:

[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
)

I am trying to sort this array into a multi-dimensional array, so that it outputs something like:

Continent
    - Country Name    
      -- Cities under Every Country

I am using PHP. Can anyone point me to a good starting point as to how I should go about doing this?

possible duplicate of [How to "flatten" a multi-dimensional array to simple one in PHP?](http://stackoverflow.com/questions/526556/how-to-flatten-a-multi-dimensional-array-to-simple-one-in-php) — Prasanth Bendra, Jul 17 '14 at 09:00
Title is misleading. The problem was to translate a multidimensional array into another multidimensional array with a different structure. — faintsignal, Dec 14 '16 at 22:22

score 10 · Accepted Answer · answered Nov 11 '13 at 17:08

$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);

score 0 · Answer 2 · answered Nov 11 '13 at 17:11

I think you just need to loop in your array and create a new one using some values as keys and some other as value, for example

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

Live Sample

score 0 · Answer 3 · answered Nov 12 '21 at 19:55

What about this solution:

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);

How to convert a Single Array into a multidimensional array in PHP?

3 Answers3

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