Jorge, Thanks for your help. which.min() on the sorted vector divided by the vector length gave me the value I was looking for (I was looking for the probability p(mean(x) | x)):
> x <- runif(1000) > x.sort <- sort(x) > x.length <- length(x) > x.mean <- mean(x) > p.mean <- which.min((x.sort - x.mean)^2) / x.length Another user pointed out a function suited for this purpose, findInterval() > p.mean <- findInterval(x.mean, xsort) / x.length Thanks for your help, David On Thu, Jun 17, 2010 at 10:15 PM, Jorge Ivan Velez <jorgeivanve...@gmail.com> wrote: > Hi David, > You might try: >> set.seed(1) >> x <- runif(10, 3, 7) >> x > [1] 4.062035 4.488496 5.291413 6.632831 3.806728 6.593559 6.778701 5.643191 > 5.516456 3.247145 >> (x-mean(x))^2 > [1] 1.308783661 0.514892188 0.007285983 2.035688832 1.958118177 1.925165288 > 2.473214156 > [8] 0.191087609 0.096348590 3.837329960 >> which.min((x-mean(x))^2) > [1] 3 >> x[which.min((x-mean(x))^2)] > [1] 5.291413 >> which.min(scale(x, scale = FALSE)**2) > [1] 3 > See ?which.min and ?scale for more information. > HTH, > Jorge > > On Thu, Jun 17, 2010 at 7:06 PM, David LeBauer <> wrote: >> >> Hello, >> >> I am interested in finding the quantile of the mean of a vector, >> something analogous to using the pnorm(), but for an mcmc chain >> instead of a distribution with known parameters. >> >> One approach would be to write a function that finds the index of x_i >> that minimizes (x-mean(x))^2 >> >> I suspect there is a function available to do this, but I can't find it? >> >> Thank you, >> >> David >> >> ______________________________________________ >> 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. > > -- David LeBauer, PhD Energy Biosciences Institute University of Illinois Urbana-Champaign 1206 W. Gregory Drive Urbana, IL 61801, U.S.A. ______________________________________________ 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.