Php array join

Question

I have the following array:

Array
(
    [0] => Array
        (
            [id] => 160
            [payment_period] => Monthly
            [plan_payment_type_id] => 171
            [payment_type_id] => 4
        )
    [1] => Array
        (
            [id] => 160
            [payment_period] => Monthly
            [plan_payment_type_id] => 172
            [payment_type_id] => 5
        )
    [2] => Array
        (
            [id] => 161
            [payment_period] => Weekly
            [plan_payment_type_id] => 173
            [payment_type_id] => 9
        )
)

I need to group this array by id. How can I do this in the best way? My conclusion should be:

Array
(
    [0] => Array
        (
            [id] => 160
            [payment_period] => Monthly
            [payment_types] => Array(
                [0] => Array(
                    [plan_payment_type_id] => 171
                    [payment_type_id] => 4
                )
                [1] => Array(
                    [plan_payment_type_id] => 172
                    [payment_type_id] => 5
                )
            )
        )
    [1] => Array
        (
            [id] => 161
            [payment_period] => Weekly
            [payment_types] => Array(
                [0] => Array(
                    [plan_payment_type_id] => 173
                    [payment_type_id] => 9
                )
            )
        )
)

Many thanks.

Answer 1

Something like that:

$output = array();
$id_array = array();
$i = 0;
foreach($input as $key=>$val) {
        if(array_key_exists($val['id'],$id_array)) {
                $pos = $id_array[$val['id']];
                $output[$pos]['payment_types'][] = array('plan_payment_type_id'=> $val['plan_payment_type_id'],'payment_type_id' => $val['payment_type_id']);
        } else {
                $output[$i] = array('id' => $val['id'],'payment_period' => $val['payment_period'],'payment_types' => array(array('plan_payment_type_id'=> $val['plan_payment_type_id'],'payment_type_id' => $val['payment_type_id'])));
                echo "Adding ",$val['id'],"\n";
                $id_array[$val['id']] = $i; 
                $i++;
        }   
}

Working link

Answer 2

You are stuck because you are trying to create an enumerated array when you really want to group this by the identifier of the array. Just use the id field as the target index:

foreach ($in as $src) {
    extract($src);
    $output[$id]["id"] = $id;
    $output[$id]["payment_period"] = $payment_period;
    $output[$id]["payment_types"][] = array(
        "plan_payment_type_id" => $plan_payment_type_id,
        "payment_type_id" => $payment_type_id,
    );
}

Of course, you can use the long variable names $ src [] instead of the evil extract () label.

, $id, id = = $id.