PHP splitting arrays into groups based on one field's value

I have an array containing arrays of names and other details, in alphabetical order. Each array includes the first letter associated with the name.

Array
(
    [0] => Array
        (
            [0] => a
            [1] => Alanis Morissette
        )

    [1] => Array
        (
            [0] => a
            [1] => Alesha Dixon
        )
    [2] => Array
        (
            [0] => a
            [1] => Alexandra Burke
        )

    [3] => Array
        (
            [0] => b
            [1] => Britney Sp开发者_如何学Goears
        )

    [4] => Array
        (
            [0] => b
            [1] => Bryan Adams
        )
)

I'd like to display them grouped by that first initial, eg:

A
-
Alanis Morissette
Alesha Dixon
Alexandra Burke

B
-
Britney Spears
Bryan Adams

etc...

Is this at all possible?

You can group them easily, even if they aren't sorted:

$groups=array();
foreach ($names as $name) {
    $groups[$name[0]][] = $name[1];
}

You don't even need to store the first initial to group them:

$names = array(
  'Alanis Morissette',
  'Alesha Dixon',
  'Alexandra Burke',
  'Britney Spears',
  'Bryan Adams',
  ...
);

$groups=array();
foreach ($names as $name) {
    $groups[$name[0]][] = $name;
}

Since your array is already sorted, you could just loop through and track the last letter shown. When it changes, you know you're on the next letter.

$lastChar = '';
foreach($singers as $s) {
    if ($s[0] != $lastChar) echo "\n".$s[0]."\n - \n";
    echo $s[1]."\n";
    $lastChar = $s[0];
}