On Fri, 2006-08-04 at 12:46 -0400, Daniel Gerlanc wrote: > Hello all, > > Consider the following problem: > > There is a matrix of probabilities: > > > set.seed(1) > > probs <- array(abs(rnorm(25, sd = 0.33)), dim = c(5,5), dimnames = > > list(1:5, letters[1:5])) > > probs > a b c d e > 1 0.21 0.27 0.50 0.0148 0.303 > 2 0.06 0.16 0.13 0.0053 0.258 > 3 0.28 0.24 0.21 0.3115 0.025 > 4 0.53 0.19 0.73 0.2710 0.656 > 5 0.11 0.10 0.37 0.1960 0.205 > > I want to sample 3 values from each row. > > One way to do this follows: > > index <- 1:ncol(probs) > > for(i in 1:nrow(probs)){ > > ## gets the indexes of the values chosen > > sample(index, size = 3, replace = TRUE, prob = probs[i, ]) > > } > > Is there a another way to do this? > > Thanks!
> t(apply(probs, 1, function(x) sample(x, 3))) [,1] [,2] [,3] 1 0.210 0.5000 0.0148 2 0.258 0.0053 0.1300 3 0.025 0.2800 0.3115 4 0.190 0.5300 0.2710 5 0.196 0.1000 0.1100 See ?apply and ?t HTH, Marc Schwartz ______________________________________________ R-help@stat.math.ethz.ch 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.