Install-Package SoftCircuits.RandomEnumerableExtensions

The RandomEnumerableExtensions class library defines Random() and Shuffle() methods. The methods are implemented as extension methods and so they are available as methods on any collection that implements IEnumerable<T> when the library is referenced and visible (via using statement).

The Random() method returns one item randomly chosen from the collection. The Shuffle() method reorders the collection . If the collection implements IList<T>, the items are shuffled in place. Otherwise, the collection is copied and shuffled.

Both the Random and Shuffle methods accept a parameter of type System.Random. If this parameter is not supplied, both functions will create their own. However, allocating your own instance of System.Random and then passing it to these functions may provide better performance and possibly a little more randomness.

The code below demonstrates the random extension methods. It starts by creating a list with sequential integers and displays that list. Next, it prints randomly chosen items from the list. And, finally, it shuffles the entire list and prints the shuffled list.

static void Main(string[] args)
{
    // Create ordered list
    List<int> list = new List<int>();
    for (int i = 1; i <= 10; i++)
        list.Add(i);

    // Create psuedo-random number generator
    Random rand = new Random();

    // Print original list
    Console.WriteLine("Original List:");
    Console.WriteLine(String.Join("\r\n", list));
    Console.WriteLine();

    // Print random items from the list
    Console.WriteLine("Random Elements:");
    Console.WriteLine(list.Random(rand));
    Console.WriteLine(list.Random(rand));
    Console.WriteLine(list.Random(rand));
    Console.WriteLine(list.Random(rand));
    Console.WriteLine(list.Random(rand));
    Console.WriteLine();

    // Shuffle and print list
    list.Shuffle(rand);
    Console.WriteLine("Shuffled List:");
    Console.WriteLine(String.Join("\r\n", list));
    Console.WriteLine();

    Console.ReadKey();
}