Fisher–Yates Shuffle

Fisher–Yates shuffle, also known as Knuth shuffle, is an algorithm for generating a random permutation of a finite set—in plain terms, the algorithm shuffles the set. The algorithm effectively puts all the elements into a hat; it continually determines the next element by randomly drawing an element from the hat until no elements remain.

• C#
• VB.Net
• C
• C++
• PHP

									function FisherYatesShuffle($data, $count)
{
	$retVal = array();
	$ind = array();
	$index = 0;

	for ($i = 0; $i < $count; ++$i)
		$ind[$i] = 0;

	for ($i = 0; $i < $count; ++$i)
	{
		do
		{
			$index = rand() % $count;
		} while ($ind[$index] != 0);

		$ind[$index] = 1;
		$retVal[$i] = $data[$index];
	}

	return $retVal;
}
								

Example

									$data = array(486, 87, 522, 111, 894, 371, 1, 39);
$retVal = FisherYatesShuffle($data, 8);
								

Output

									retVal: { 87, 1, 39, 894, 371, 522, 111, 486 }