This function allows you to sort a php array by subelement values, this should be used in conjunction with the array_element function.

gistfile1.php

<?php

function array_sort($array, $key, $order = 'asc', $sort_flags = SORT_REGULAR)
{
	if( ! is_array($array))
	{
		return FALSE;
	}

	foreach($array as $k=>$v) 
	{
		$b[$k] = array_element($v, $key);
	}

	switch($order)
	{
		case 'asc':
			asort($b, $sort_flags);
		break;

		case 'desc': 
			arsort($b, $sort_flags);
		break;
	}

	foreach($b as $key=>$val) 
	{
		$c[$key] = $array[$key];
	}

	return $c;
}