Hello Rainer, You could also get a very exact approximation using our package distr; e.g.
library(distr) B1 <- Binom(prob = 0.4, size = 20) B2 <- Binom(prob = 0.2, size = 10) B3 <- B1+B2 #convolution! plot(B3) hth, Matthias Rainer M. Krug schrieb: > Frede Aakmann Tøgersen wrote: > >> Perhaps >> >> http://stinet.dtic.mil/cgi-bin/GetTRDoc?AD=ADA266969&Location=U2&doc=GetTRDoc.pdf >> >> is something that you can use? >> > > Thanks a lot - that might help. > > Rainer > > >> >> Best regards >> >> Frede Aakmann Tøgersen >> Scientist >> >> >> UNIVERSITY OF AARHUS >> Faculty of Agricultural Sciences >> Dept. of Genetics and Biotechnology >> Blichers Allé 20, P.O. BOX 50 >> DK-8830 Tjele >> >> Phone: +45 8999 1900 >> Direct: +45 8999 1878 >> >> E-mail: [EMAIL PROTECTED] >> Web: http://www.agrsci.org >> >> This email may contain information that is confidential. >> Any use or publication of this email without written permission from Faculty >> of Agricultural Sciences is not allowed. >> If you are not the intended recipient, please notify Faculty of Agricultural >> Sciences immediately and delete this email. >> >> >> >> >> >> >>> -----Oprindelig meddelelse----- >>> Fra: [EMAIL PROTECTED] >>> [mailto:[EMAIL PROTECTED] På vegne af Rainer M Krug >>> Sendt: 24. oktober 2007 09:11 >>> Til: Charles C. Berry >>> Cc: r-help >>> Emne: Re: [R] analytical solution to Sum of binominal >>> distributed random numbers? >>> >>> Hi Charles >>> >>> thanks for the pointing out that size and prob can be vectors >>> as well - I tried it out but used 1 as the number of >>> observations, assuming that and it only gave me one randon >>> mumbewr (as it should be but not expected). >>> >>> But I was more looking at a analytical solution, as I have to >>> sum up a huge number of random numbers. But I am going to try >>> your solution as it should be much faster already. >>> >>> Thanks >>> >>> Rainer >>> >>> >>> Charles C. Berry wrote: >>> >>>> ?rbinom >>>> >>>> only says: >>>> >>>> size: number of trials (zero or more). >>>> >>>> prob: probability of success on each trial. >>>> >>>> >>>> But they can be vectors. >>>> >>>> BTW, you were aked to "PLEASE ... provide minimal, self-contained, >>>> reproducible code." >>>> >>>> What you show cannot run without correction. >>>> >>>> Most likely, you intended size(n) to be the n-th element of >>>> >>> the vector >>> >>>> 'size', which in R is written 'size[ n ]' . >>>> >>>> In which case >>>> >>>> sum (rbinom( length(prob) , size, prob ) ) >>>> >>>> works. >>>> >>>> Chuck >>>> >>>> On Tue, 23 Oct 2007, Rainer M Krug wrote: >>>> >>>> >>>>> Hi >>>>> >>>>> I have two vectors, prob and size, and I want to add the random >>>>> deviates of these two, i.e. >>>>> >>>>> sum( >>>>> sapply( >>>>> 1:length(prob), >>>>> function(n){ rbinom(1, size(n), prob(n) } >>>>> ) >>>>> ) >>>>> >>>>> My problem is that I have to do this for a large number of value >>>>> combinations. Is there a faster way of doing this? >>>>> >>>>> Rainer >>>>> >>>>> ______________________________________________ >>>>> 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. >>>>> >>>>> >>>> Charles C. Berry (858) 534-2098 >>>> Dept of >>>> >>> Family/Preventive Medicine >>> >>>> E mailto:[EMAIL PROTECTED] UC San Diego >>>> http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego >>>> 92093-0901 >>>> >>>> ______________________________________________ >>>> 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. >>> >>> > > ______________________________________________ > 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.
