Preg_match数组键

Question

I have it like this:

$data = array(
    "City_0" => "London",
    "City_1" => "Paris",
    "City_2" => "Lisbon",
    "City_3" => "Berlin"
    );

plus some other data in that same array.

User will select only one of these and what I need is:

1. Check with preg_match to get all keys that starts with "city_"
2. find key which has value (it is not empty), take that value
3. assign it to new key
4. remove all "city_" keys
5. add new key to array with the name "chosen_city" which will contain that value

What I tried:

foreach ($data as $key => $value) {
    $matches = preg_match('/city_/i', $key);

    if ($value != "") {
        $newValue = $value;

        break;
    }
}

$data['chosen_city'] = $newValue;


print_r($data);

This works partially, how can I remove all previous "city_" keys from array in that if statement?

NOTE: I have other keys in array, and I don't want to remove them as well.

Input array:

$data = array(
        "City_0" => "London",
        "City_1" => "Paris",
        "City_2" => "Lisbon",
        "City_3" => "Berlin",
        "distance" => "5 km",
        "days" =>   "7",
        "tickets" => "2",
        "discount" => "10%",
        );

Expected output:

$data = array(
            "chosen_city" => "Berlin",
            "distance" => "5 km",
            "days" =>   "7",
            "tickets" => "2",
            "discount" => "10%",
            );

Thanks.

Answer 1

Please put unset for example code :

$data = array( "City_0" => "London", "City_1" => "Paris", "City_2" => "Lisbon", "City_3" => "Berlin");
foreach($data as $key => $value){
    $matches = preg_match('/city_/i', $key);

    if($matches && $value != ""){
        $newValue = $value;
        unset($data[$key]);
    }elseif($matches){
        unset($data[$key]);
    }

}

$data['chosen_city'] = $newValue;