Hi Greg, Thanks, this makes sense. I can envision the call to the sample fn like you are discribing. Any ideas on how to construct the vector? I still am unclear about that.
Thanks, Dan On Mon, Jun 23, 2014 at 5:26 PM, Greg Snow <538...@gmail.com> wrote: > The sample function can be used to sample discrete values with > designated probabilities. I would just construct your list of 5 > values based on the selected value (duplicating end values if needed, > so a choice of x=0 would be the vector c(0,0,0, 0.125, 0.25) ), then > sample from this vector with the probabilities that you specify. > > On Mon, Jun 23, 2014 at 3:11 PM, Dan Abner <dan.abne...@gmail.com> wrote: >> Hi all, >> >> I have the following situation and a good efficient way to perform >> this operation in R has not come to me. Any suggestions/input are >> welcome. >> >> I have a user-defined parameter (let's call it x) whose value is >> selected from a set of possible values (j). Once the user selects one >> of the values of j for x, then I need to map a probability >> distribution to the values of j such that the middle probability of >> .5385 (see probs below) is associated with the value of x and the tail >> probabilities are assigned to the 2 values below x and 2 values above >> x in j. Therefore, in the example below: >> >> >> x<-.250 >> j<-c(0.000,0.125,0.250,0.375,0.500,0.625,0.750,0.875,1.000) >> probs<-c(0.02307692,0.20769231,0.53846154,0.20769231,0.02307692) >> >> probabilities would be assigned to the values of j as such: >> >> value probability >> 0 0.023077 >> 0.125 0.207692 >> 0.25 0.538462 >> 0.375 0.207692 >> 0.5 0.023077 >> >> And then 1 value of j is selected based on the associated probability. >> Any ideas on an efficient way to do this? >> >> An added dimension of complexity is when the value of x is selected >> near the parameter boundary of j. If x = 0, then the easiest thing I >> can think of is to assign probabilities as: >> >> value probability >> 0 0.76923077 >> 0.125 0.207692 >> 0.25 0.023077 >> >> However, I am open to other possibilities. >> >> Any assistance is appreciated. >> >> Thanks, >> >> Dan >> >> ______________________________________________ >> 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. > > > > -- > Gregory (Greg) L. Snow Ph.D. > 538...@gmail.com ______________________________________________ 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.
