Inner workings or orderby Rnd.next

[jrmourning]

I am trying to understand the internal logic of how Orderby actually re-orders when using Orderby with random.Next.

For Example in the following how is the random number actually used to do the reordering?

Dim deck = Enumerable.Range(1, 52)

deck = deck.OrderBy(Function(n) rng.Next)

I would appreciate an easy not too technical explanation.

[Frinavale]

I have no idea what you are doing with the random number.
The Enummerable.Ord erBy() method is used to sort the elements in the enumeration. Using a random number is kind of defeating the purpose because it would be randomizing instead of sorting. See the link for more details.



-Frinny

[jrmourning]

this was part of the code in a Dan Mabbutt article concerning random numbers. the entire code block was

Dim rng As New Random
'Create the deck.
Dim deck = Enumerable.Range(1, 52)
'Shuffle the deck.
deck = deck.OrderBy(Function(n) rng.Next)
'Deal four hands of five cards.
Dim hands(3) As List(Of Integer)
For i = 0 To 3
    hands(i) = deck.Skip(i * 5).Take(5).ToList()
Next

I understand the effect of the code; however, when stepping through it, the OrderBy Rng.Next cycles through each of the members of deck. I am wondering about the mechanics of exactly how it is randomizing the members of deck. When it examines the first member is it selecting a subsequent member at random and replacing the member it is addressing? Is it then simply placing the replaced member at the position from which it took the replacement?

I am interested in the details of the process that is being performed.

Dan's article is at http://visualbasic.about.com/od/usin...ndintarray.htm

[Frinavale]

Well, if your list was originally sorted (in order) and you sort it again based on a random number, then your sorted list will not be sorted any more.

-Frinny