Generate an XML structure from a 3d array

How to nicely display the data structure. Below paste my multidimensional array, please help

Array
(
    [1] => Array
        (
            [0] => Array
                (
                    [LP] => 1
                    [Produkt] => product1
                )
        )
    [2] => Array
        (
            [0] => Array
                (
                    [LP] => 2
                    [number] => 157/03/2014
                    [Produkt] => product1
                )
            [1] => Array
                (
                    [LP] => 2
                    [number] => 157/03/2014
                    [Produkt] => product2

=== My CODE ==============================================

foreach ($a as $date) {
    $output .= "\t\t\t<ID>". $date[0]['LP']."</ID>\n";

    second foreach for product {
        $output .= "\t\t\t<Produkt>". Produkt ."</Produkt>\n";
    }
}

Because I want to have something like this:

1
    -Product1
2
    -Product1
    -Product2
3
    -Product1
4
    -Product1
    -Product2

Because it appears that you want your output to be XML, i'd suggest the following code:

function arraytoxml($xmlObj,$data) {
    foreach ($data as $key => $value) {
        if(is_array($value)) {
            if(is_numeric($key)) {
                $key = 'item_' . $key;
            }
            $subnode = $xmlObj->addChild("$key");
            arraytoxml($subnode,$value);
        } else {
            $xmlObj->addChild("$key","$value");
        }
    }
    return $xmlObj;
}

$xml = new SimpleXMLElement("<?xml version=\"1.0\"?><return></return>");
$return_xml = arraytoxml($xml,$data);
print($return_xml);

Where $data is your associative array.