Convert array with 3-element rows into hierarchical array with 3 levels

Question

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 group this array into a new multi-dimensional array structure, so that it outputs something like:

Continent
    - Country Name    
      -- Cities under Every Country

Exact desired result:

array (
  'Latin America' => 
  array (
    'Venezuela' => 
    array (
      0 => 'Caracas',
    ),
  ),
  'Middle East' => 
  array (
    'Egypt' => 
    array (
      0 => 'Cairo',
    ),
    'United Arab Emirates' => 
    array (
      0 => 'Abu Dhabi',
      1 => 'Dubai',
    ),
  ),
  'North America' => 
  array (
    'Canada' => 
    array (
      0 => 'Montreal',
    ),
  ),
)

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);