php - Array intersect on key in array?

Question

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 inefficent...

Answer 1

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