如何简化我的PHP数组

Question

I have a simple array of data, and I would like to make it multidimensional. To keep things simple, I've written below an array that reflects what I've got, and another that reflects how it should be.

The problem is I don't know the keys like 'europe' or 'france', or 'paris'.

I need to determine if the continent is a new key, so I make an array with it. Same with the countries, then cities etc.

I have this :

Array
(
    [0] => Array
        (
            [continent]     => europe
            [country]       => france
            [city]          => paris
            [monument]      => tour eiffel
        )

    [1] => Array
        (
            [continent]     => europe
            [country]       => england
            [city]          => london
            [monument]      => big ben
        )

    [2] => Array
        (
            [continent]     => australia
            [country]       => australia
            [city]          => sydney
            [monument]      => opera
        )

    [3] => Array
        (
            [continent]     => america
            [country]       => usa
            [city]          => new york
            [monument]      => empire state building 
        )

    [4] => Array
        (
            [continent]     => america
            [country]       => usa
            [city]          => new york
            [monument]      => statue of liberty 
        )
)

I need that :

Array
(
    [0] => Array (
        [europe] => Array (
            [france] => Array (
                [paris] => Array (
                    [0] => eiffel tower
                )
            )
            [england] => Array (
                [london] => Array (
                    [0] => big ben
                )
            )
        )   
        [australia] => Array (
            [australia] => Array (
                [sydney] => Array (
                    [0] => opera
                )
            )
        )
        [america] => Array (
            [usa] => Array (
                [new york] => Array (
                    [0] => empire state building
                    [1] => statue of liberty
                )
            )
        )
    )
)

Any ideas ?

Answer 1

Use a loop -

$new = array();

foreach($array as $data) {
    $new['continents'][$data['continent']][$data['country']][$data['city']][] = $data['monument']; 
}

Output

array(1) {
  ["continents"]=>
  array(3) {
    ["europe"]=>
    array(2) {
      ["france"]=>
      array(1) {
        ["paris"]=>
        string(11) "tour eiffel"
      }
      ["england"]=>
      array(1) {
        ["london"]=>
        string(7) "big ben"
      }
    }
    ["australia"]=>
    array(1) {
      ["australia"]=>
      array(1) {
        ["sydney"]=>
        string(5) "opera"
      }
    }
    ["america"]=>
    array(1) {
      ["usa"]=>
      array(1) {
        ["new york"]=>
        string(17) "statue of liberty"
      }
    }
  }
}