Just for clarification : this is an extension, where you can take the probability of switching to any possible value. Take into account that the p-value in the function rbinom is 1-P for the switching of the sign.
On Tue, Nov 18, 2008 at 11:21 PM, joris meys <[EMAIL PROTECTED]> wrote: > The function rbinom might be a solution. > > Try following simple program : > vec <- c(-1,1,-1,1,1,-1,-1,1,1) > > inv <-rbinom(length(vec),1,0.5) > inv <-ifelse(inv==0,-1,1) > > vec2 <- vec*inv #switches sign with p=0.5 > > In this, inv is a random binomial vector, where the probability for > being 1 is 0.5 in all positions. Changing the values of 0 in this > vector to -1, gives you a vector you can multiply with the original > one to change the sign with a probability of 0.5 for all positions > > Kind regards > Joris > On Tue, Nov 18, 2008 at 6:11 PM, Salas, Andria Kay <[EMAIL PROTECTED]> wrote: >> To clear up a question regarding my earlier posting regarding random changes >> in a vector: >> >> Say you have a vector (1, -1, -1, 1, 1, -1). I want each value in the >> vector to have a probability that it will change signs when this vector is >> regenerated. For example, probability = 50%. When the vector is >> regenerated, the first value in the vector (1) has a 50% chance of switching >> to -1. If I regenerated this vector 10 times, 5 of the times it would >> switch to -1. Similarly, I need each value in the vector to have this same >> probability of switching signs when the vector is regenerated, and each >> value's chances of doing so is independent of the other values. So the >> second value (-1) also has a 50% chance of switching to 1, and whether or >> not it does so is independent of if the first value changes from 1 to -1 >> (also a 50% probability). >> >> I hope this clears up the confusion, and I would appreciate any help anyone >> can provide! >> ______________________________________________ >> 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.
