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Topic: Lottery numbers & non repeating values tool (Read 1137 times) |
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MarsFS
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Re: Lottery numbers & non repeating values tool
« Reply #8 on: Sep 1st, 2017, 10:20pm » |
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Here's another version using a knuth shuffle with multiple lines and sorted and formatted output:
Code: REM Lotto number generator max%=49 nums%=7 DIM allNumbers(max%) DIM sorted(max%) REM Creat a fresh set of numbers FOR T%=1 TO max% allNumbers(T%)=T% NEXT REPEAT PROC_newnumbers key$ =GET$ UNTIL key$="q" OR key$="Q" PRINT "Done" END DEF PROC_newnumbers LOCAL T%,N%,C%,J%,A$ CLS PRINT "Lotto Number Picker" PRINT "-------------------" INPUT "How many lines (1-18): ", J% IF J%<2 OR J%>18 THEN J%=1 A$="is 1 line" ELSE A$="are "+STR$(J%)+" lines" ENDIF CLS PRINT "Here ";A$;" of ";STR$(nums%);" numbers for Lotto Max:": PRINT FOR C%=1 TO J% REM randomly shuffle the numbers FOR T% = max% TO 2 STEP -1 SWAP allNumbers(T%),allNumbers(RND(T%)) sorted(T%)=0 NEXT sorted(1)=0 REM choose a random set and sort N%=RND(max%-nums%+1) FOR T%=N% TO N%+nums%-1 sorted(allNumbers(T%))=allNumbers(T%) NEXT REM print sorted list PRINT "Line ";RIGHT$("0"+STR$(C%),2);": "; FOR T%=1 TO max% IF sorted(T%) PRINT RIGHT$(" "+STR$(sorted(T%)),2);" "; NEXT PRINT NEXT PRINT:PRINT "Press any key for more numbers, Press 'Q' to quit" ENDPROC
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Richard Russell
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Re: Lottery numbers & non repeating values tool
« Reply #9 on: Sep 2nd, 2017, 11:15am » |
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on Sep 1st, 2017, 10:20pm, MarsFS wrote:| Here's another version using a knuth shuffle with multiple lines and sorted and formatted output |
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Nice, and works without modification on both BB4W and BBCSDL!
For my own interest I ran some tests on how many calls to RND(52) might be necessary before a specific unique number is returned. The answer seemed to be that needing to call it more than 900 times is not that unlikely (the highest I saw was 996)! Obviously typically it will be fewer, but it illustrates the uncertainty in execution time that can arise from using that technique.
Richard.
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Leo
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Re: Lottery numbers & non repeating values tool
« Reply #10 on: Sep 2nd, 2017, 4:00pm » |
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Although I can't disagree with the logic behind "run time is unpredictable" - the lottery case here is a complete frippery. It's just a "throwaway" toy.
Of course I wouldn't use the technique I did for anything approaching any seriousness but I stand by my choice for the lottery case because..
a) It's a complete frippery.
b) The program is very short.
c) We're only selecting ANY 7 numbers from 49 so there's no chance of this taking forever.
d) The quality of the random numbers is irrelevant because any 7 will have an equal chance of winning.
I also ran some trials (a lot).
The maximum number of lookup clashes in any single line was 6 - sounds a lot.
However, in creating 10000 lottery lines a repeat lookup was necessary in 6.7% of cases - no problem.
Henceforward I will use the dates of my children's birthdays to derive (winning) lottery lines. 
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Richard Russell
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Re: Lottery numbers & non repeating values tool
« Reply #11 on: Sep 2nd, 2017, 4:43pm » |
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on Sep 2nd, 2017, 4:00pm, Leo wrote:| I stand by my choice for the lottery case because... |
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That's fine, with those qualifications. The trouble is that people may adapt the code for other applications without appreciating its limitations (for example they may come upon it years later as the result of a search).
My experience is that there is widespread misunderstanding about pseudo-random numbers and statistics, and although it's unlikely that anybody would use BBC BASIC for an online casino program, or something like that, it's not impossible.
Several years ago I wrote this article at the Wiki to draw attention to some of the pitfalls. It includes simple lottery draw and card shuffling programs. It's out of date to the extent that BBC BASIC no longer uses the value of TIME as a seed.
Richard.
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Leo
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Re: Lottery numbers & non repeating values tool
« Reply #12 on: Sep 2nd, 2017, 9:00pm » |
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Thanks for that link Richard - very good article.
Although I'm gradually working my way through the info in the wiki, I admit I haven't read that one before. Everybody who uses BB4W should go and rummage through the wiki - there's so much excellent information in there.
I use CryptGenrandom a lot for 'professional' use. I think I posted something here that used it a short time ago - but I don't remember what right now. (My memory ain't what it used to be).
Thanks again for the info.
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