Mary -- The dmultinomial function (try ?Multinomial, noting that it is an upper case M) has a "log" option, which, if set to TRUE, returns logarithms of probabilities, but that is for computing probabilities, not generating samples. Perhaps the "long" you referred to is a misprint for "log?"
In any case, try ?Multinomial, and give rmultinom() another try. Note, however, that its output gives the _number_ of each of the sampled items produced in a single sample, not the sequence of draws. If you need the sequence, then I think that the reply from Erik Iverson tells you how best to proceed. Ben -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mary Black Sent: Tuesday, March 18, 2008 5:29 PM To: r-help@r-project.org Subject: [PS] [R] rmultinomial() function After scouring the online R resources and help pages, I still need clarification on the function rmultinomial(). I would like to create a vector, say of 100 elements, where every element in the vector can take on the value of 0, 1 or 2, and where each of those values have a specific probability. ie. the probability a given element in the vector = 0 is 0.06, 1 = 0.38, 2 = 0.56 (probabilities sum to 1). Can I use rmultinomial() function to do this? The following code does not seem to produce the result I need, but this sort of code is all I could find the R "help" pages: > rmultinomial(100,c(0.06,0.38,0.56)) [1] 3 29 68 > rmultinomial(100,c(0.06,0.38,0.56),long=TRUE) [1] 3 3 2 2 3 2 3 3 2 3 2 3 3 3 2 2 3 3 2 3 1 2 3 3 3 3 3 3 2 3 3 2 3 3 3 2 3 2 2 3 2 3 2 3 3 3 2 1 3 3 1 [52] 2 3 2 2 3 3 2 2 2 1 3 3 2 3 3 3 3 2 3 3 3 3 2 3 2 3 3 2 3 3 2 3 3 2 3 2 3 3 2 3 3 3 2 3 2 2 2 2 2 Also, I don't really understand the difference between the default long=FALSE and long=TRUE. The R "help" simply states that you use "long TRUE to choose one generator, FALSE to choose another one"; however I could not find any documentation that described what the difference between those generators is. Any clarification would be greatly appreciated! Thanks, Mary ______________________________________________ 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.
