Hi Daniel, Great! Many thanks!
Dan On Mon, Jun 23, 2014 at 8:23 PM, Daniel Nordlund <djnordl...@frontier.com> wrote: > Something like this could work > > > x <- 0.250 > new_sample <- function(xx) { > 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) > jj <- c(0,0,j,1,1) > ndx <- which(j == xx) > sample(jj[ndx:(ndx+4)], size=1, p=probs, replace=TRUE) > } > new_sample(x) > > > > Daniel Nordlund > Bothell, WA USA > > >> -----Original Message----- >> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] >> On Behalf Of Dan Abner >> Sent: Monday, June 23, 2014 3:19 PM >> To: Greg Snow >> Cc: r-help@r-project.org >> Subject: Re: [R] Custom sampling method in R XXXX >> >> 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. > > ______________________________________________ > 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.