On Sun, Apr 29, 2012 at 4:38 PM, Vale Fara <vale...@gmail.com> wrote: > Hi, > > thank you both for your replies, I really appreciate it! > > To Mike: yes, random integers. Can I use the function round() as in > the example with 5 random numbers below? > > To Billy: for the second part I got an error, but it may be that I > didn't properly set "i"...? > Here is the R output: > x <- runif(60 , 0 , 10) # 60 numbers from 0 to 10 >> x > [1] 3.29208009 8.62643979 3.40762875 0.35224714 6.78760173 4.72160818 etc > y<- runif(60, 15 , 25) # same as above , from 15 to 25 >> y > [1] 18.48391 24.44361 23.20955 16.61257 23.06074 17.71158 23.67585 19.31675 > etc > i <- 12 >> i > [1] 12 >> for( i in 1:length(x)) { > + z = x[i] + y[i] > + return z} > Errore: unexpected symbol in: > "z = x[i] + y[i] > return z"
I noted here (http://tolstoy.newcastle.edu.au/R/e17/help/12/04/11923.html) but I think it got caught by the spam filters (for whatever reason) that this is invalid code and you simply need: z <- x + y and the magic of vectorization will save the day. Michael > > To all: I attach an example with only 5 random numbers > > step 1. random number generation > x <- round(runif(5 , 0 , 10) ) > < x > [1] 2 1 0 6 8 > y <- round(runif(5 , 15 , 25) ) >> y > [1] 21 24 22 22 19 > > step2. matching of numbers from x and y to create lotteries > lottery 1: 2$ with 50% probability vs. 21$ with 50% of probability > (Expected value: 2*0.5+21*0.5=11.5) > lottery 2: 1$ with 50% probability vs. 24$ with 50% of probability > (Expected value: 1*0.5+24*0.5=12.5) > lottery 3: 0$ with 50% probability vs. 22$ with 50% of probability > (Expected value: 0*0.5+22*0.5=11) > lottery 4: 6$ with 50% probability vs. 22$ with 50% of probability > (Expected value: 6*0.5+22*0.5=14) > lottery 5: 8$ with 50% probability vs. 19$ with 50% of probability > (Expected value: 8*0.5+19*0.5=13.5) > > step 3. Form step 2, I know that the min EV of these lotteries is 11 > and the max EV is 14. > The difference is: max EV - min EV = 3. > I need a difference of 5 > > How to do this? > > Valeria > > > > 2012/4/29 billy am <wickedpu...@gmail.com>: >> Interesting set of question.. I am completely new to R but let me try my >> luck. >> >> Random number in R >> >> x <- runif(60 , 0 , 10) # 60 numbers from 0 to 10 >> y<- runif(60, 15 , 25) # same as above , from 15 to 25 >> >> The second part though. Do you mean , >> >> for( i in 1:length(x)) { >> z = x[i] + y[i] >> return z >> } >> >> something like that? No idea about the third part though. >> >> regards >> Billy >> >> On Sun, Apr 29, 2012 at 9:29 AM, Mike Miller <mbmille...@gmail.com> wrote: >>> >>> On Fri, 27 Apr 2012, Vale Fara wrote: >>> >>>> I am working with lotteries and I need to generate two sets of uniform >>>> random numbers. >>>> >>>> Requirements: >>>> 1) each set has 60 random numbers >>> >>> >>> random integers? >>> >>> >>>> 2) random numbers in the first set are taken from an interval (0-10), >>>> whereas numbers in the second set are taken from a higher interval >>>> (15-25) >>> >>> >>> Depends on if you mean integers. R has functions. Here's one: >>> >>> http://www.astrostatistics.psu.edu/su07/R/html/stats/html/Uniform.html >>> >>> >>> >>>> 3) numbers generated in the first set should be matched to numbers in >>>> the second set (row by row) so that the expected value of each couple >>>> of random numbers (i.e. of each lottery) is around to a given value >>>> (12.5 +/- 5, where 12.5 is the median value of the interval extremes). >>> >>> >>> Do you mean that the mean for the pair of numbers must be between 7.5 and >>> 17.5, inclusive? That means the sum must be from 15 to 35. Well, you are >>> in luck because if you make the numbers as you suggested above, that will >>> happen -- you don't have to do anything special to make it happen. >>> >>> >>> >>>> For the computation of the expected value, the probabilities in each >>>> lottery are ½ and ½. >>> >>> >>> For what outcome? You lost me. >>> >>> >>> >>>> How do this? Any help given would be greatly appreciated. >>> >>> >>> I hope that helps. >>> >>> Mike >>> ______________________________________________ >>> R-help@r-project.org mailing list >>> https://stat.ethz.ch/mailman/listinfo/r-help >>> PLEASE do read the posting guide >>> http://www.R-project.org/posting-guide.html >>> and provide commented, minimal, self-contained, reproducible code. >>> >> >> >> >> -- >> http://use-r.com - R Statistics Scripting & Programming Language Online >> Community Home >> http://bam.domainpool.com - Domains For Sale >> http://SQLHack.net - Tech Blog/Tutorials >> >> ------------------------------------------------------------------------------------ >> >> MCSA (Security) , MCSA , CCNA , LPIC - Lvl 1 , Security+ , Network+ , A+ > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.