Question

So I am a bit stuck here, I can do it with foreach loop but I want to find a cleverer way of doing it.

Update: There was something that I’ve missed in the question. The arrays may come in random order and in different length thus having different keys. Examples below updated.

Here is the case:

Array1

array (
    slug1 => England,
    slug2 => France,
    slug3 => Italy,
    slug4 => Germany,
)

Array2

array (
    slug2 => 215,
    slug1 => 168,
    slug4 => 55,
    slug5 => 149,
    slug3 => 40,
    slug6 => 137,
)

I want to intersect those arrays and build new one which has the following elements:

array (
    168 => England,
    215 => France,
    40 => Italy,
    55 => Germany,
)

Note: elements are not ordered though that could be achieved easily.

Answer 1

Answer to Original Question

You can use array_combine it creates an array by using one array for keys and another for its values

$array1 = array(
        "slug1" => "England",
        "slug2" => "France",
        "slug3" => "Italy",
        "slug4" => "Germany");

$array2 = array(
        "slug1" => "168",
        "slug2" => "215",
        "slug3" => "40",
        "slug4" => "55");

$final = array_combine($array2, $array1);

echo "<pre>";
print_r($final);

Output

Array
(
    [168] => England
    [215] => France
    [40] => Italy
    [55] => Germany
)

See Live Demo

Answer to Updated Question

Update: There was something that I've missed in the question. The arrays may come in random order and in different length thus having different keys. Examples below updated.

$array1 = array(
        "slug1" => "England",
        "slug2" => "France",
        "slug3" => "Italy",
        "slug4" => "Germany");

$array2 = array (
        "slug2" => 215,
        "slug1" => 168,
        "slug4" => 55,
        "slug5" => 149,
        "slug3" => 40,
        "slug6" => 137);



$final = customCombine($array2, $array1);

echo "<pre>";
print_r($final);

Output

Array
(
    [215] => France
    [168] => England
    [55] => Germany
    [40] => Italy
)

Function Used

function customCombine($keys, $arr) {
    $t = array();
    foreach ( $keys as $k => $val ) {
        isset($arr[$k]) and $t[$val] = $arr[$k];
    }
    return $t;
}