对无序数组进行排序，并使用字母键将其变为多维数据？

I have a form where you type in different movies and separate them with "|". The database currently contains:

Spider-man|Spider-man 2|Spider-man 3|Apple|Google|Banana|Citrus

I have done an explode() of this text string so each title goes into an array:

$collection = explode('|', $collection);

For the sake of keeping things sorted alphabetically, I did this:

array_multisort($collection);

So far it's alright. However, now I need to make this array multidimensional with each key corresponding the letter the values start with. It should become like this:

Array(
    [A] => Array(
        'Apple'
    )
    [B] => Array(
        'Banana'
    )
    [C] => Array(
        'Citrus'
    )
    [G] => Array(
        'Google'
    )
    [S] => Array(
        'Spider-man',
        'Spider-man 2',
        'Spider-man 3'
    )
)

How can I achieve this?

Thanks in advance, Filip

Not the way you should be storing things in the database. You should have a table that relates to that one that holds the movies each in its own row. That being said:

//array_multisort($collection); // don't need this
sort($collection);
foreach($collection as $movie) {
    $result[$movie[0]][] = $movie;
}

If there might be some movies that start with a lowercase letter, then:

foreach($collection as $movie) {
    $result[strtoupper($movie[0])][] = $movie;
}
ksort($result);

There is no built-in function for that. You need to craft something on your own. Like this:

$string = 'Spider-man|Spider-man 2|Spider-man 3|Apple|Google|Banana|Citrus';
$result = array();
foreach(explode('|', $string) as $item) {
    $firstLetter = $item[0];
    if(!isset($result[$firstLetter])) {
        $result[$firstLetter] = array();
    }
    $result[$firstLetter][] = $item;
}

ksort($result);
var_dump($result);

$input = 'Spider-man|Spider-man 2|Spider-man 3|Apple|Google|Banana|Citrus';

$collection = array();
$movies = explode('|', $input);

sort($movies);

foreach ($movies as $movie) {
    $collection[strtoupper($movie[0])][] = $movie;
}

print_r($collection);