phparrayskeyintersection

Get intersections between the keys of an associative array and the values of an indexed array

I have an array that has countries:

array(
    'AF' => 'AFGHANISTAN',
    'AL' => 'ALBANIA',
    'DZ' => 'ALGERIA',
    'AS' => 'AMERICAN SAMOA',
);

and I have another array that has some of the keys in it

array('AL', 'DZ');

I want to call a function that will take both arrays as parameters and return

array(
    'AL' => 'ALBANIA',
    'DZ' => 'ALGERIA',
);

I know php has built in functions to compare the keys, or the values, but it seems those functions all expect you to have two 1D arrays or two 2D arrays.

I could loop over array_keys() for the first array and do a in_array() check on each key, but that seems really inefficient.

Solution 
  • $selection = array('AL', 'DZ');
$filtered = array_intersect_key($countries, array_flip($selection));
var_dump($filtered);