Hi guys, What would you think is the fastest way to generate a list of random numbers, without any doubles. At the moment I am using the following loop: do generate random number do check whether number is in arraylist "uniques" (building if not) if so EXIT and repeat generate random numberloop until noDoubles UNTIL all numbers are generated I want to use this for shuffling a deck of cards, but then a million times to simulate the probability of certain "hands" in poker. thnx in advance Marc PS: I had a thread a while ago concerning this problem but never tried to improve the speed.
I don't think you can get much faster than this. It doesn't generate unwanted random numbers. Every generated number is valid. Code: Sub Globals 'Declare the global variables here. Dim Deck(52) ' holds the shuffled cardsEnd SubSub App_Start AlCards.Clear ' ArrayList - clear in case used before For i = 0 To 51 AlCards.Add(i) ' stick all the cards in the array list Next For i = 0 To 51 r = Rnd(0, 52-i) Deck(i) = AlCards.Item(r) ' add card to deck AlCards.RemoveAt(r) 'remove it from array list Next For i = 0 To 51 ' this bit just for display msg = msg & " " & Deck(i) Next Msgbox(msg)End Sub
In an earlier project of mine, (ahem) I picked 2 random numbers and swapped the array contents. eg. Dim Deck(52) temp=0 b=0 c=0 For a = 1 to ?? 'as many times as you want. b=rnd c=rnd temp = deck(b) deck(b)=deck(c) deck(c)=temp next a This would work for shuffling the cards. Not sure it answers your question though
Better late posting to this thread than never, even if I was here first http://www.basic4ppc.com/forum/showthread.php?t=620&highlight=cards
Hi Linecutter, Thnx for your answer. I remember the thread (think I started it) and I used your solution in a different program. Now I wanted to know what the fastest way (after compiling) would be, as I like to use this in a simulation. Marc
I don't think that you can do better than agraham's (or mine) for the "player vs. computer" scenario. Then again if you are going to do a million simulations you could probably take some shortcuts... Just draw a "hand" of cards from the unshuffled pack, rather than shuffling & then drawing a hand Only compare suits if they are going to matter (most hands will be determined by face value & not sets of the same suit)
Thanks, that is surely one approach that will work. I thought of creating a limitless gigantic "deck" and drawing hands from that and then discard the hands that hold thesame cards. Maybe that would speed up the process..... Marc
I don't think that that's going to help... [A couple of assumptions: you are drawing 2 hands to see which wins vs the other & that there are 52 unique cards in the raw materials (deck) for each hand of the competition)] The chance of a duplicate card, in a 2*5 card game is: 1/51 + 1/50 + ... 1/42. Very roughly that's 10%. i.e. you'll have to redraw 1/10 of your hands, plus 1/10 of those. That would mean that 1/9 of all attempts to play would be invalid, or alternatively 1.111111 times more attempts are required in order to complete your run than if you'd adopted a more foolproof method of drawing a hand. You will probably gain more from streamlining your question than speeding up the iterations... Reference points: My own software (in <ahem> another basic & archery related) MonteCarlo Method Bootstrapping
@ Linecutter, yes you're right of course. Your assumptions are correct. I thought that being "off" a percent or two wouldn't matter for a guess in winning probabilities. But then, as ever, I want to make it perfect first, then maybe "cheat" later....gaining speed. BTW: very interesting software you have there. I am a great fan of simulations, statistics etc. At the moment I am programming dealing hands and an evaluation routine for the dealt hand. Then I will make some tables for faster access and computing probabilities by doing simulations. i have to give in some to compensate for the lack of speed on a ppc here I think. Thnx Marc
