What is the problem that you see? (I think the trouble is that Laplace density is not smooth at x=0, while a kernel density estimate returns a smooth density)
It would help to know what you are trying to achieve with this exercise... Giovanni > Date: Thu, 05 Nov 2009 14:36:44 +0100 > From: Justine Rochon <justine.roc...@klinik.uni-regensburg.de> > Sender: r-help-boun...@r-project.org > Cc: r-help@r-project.org > Precedence: list > > Hi Duncan, > > Thank you for your e-mail. > > It works for the uniform distribution, but I have trouble with the exponential > distribution: > > x <- rexp(10000) > ex_x <- c(-x, x) > den <- density(ex_x) > plot(den$x, 2*den$y, xlim=c(0,5), type="l") > > Best regards, > > Justine > > > > > > > ________________________ > Justine Rochon > - Biostatistician - > Center for Clinical Studies > University Hospital Regensburg > Franz-Josef-Strauß-Allee 11 > D-93053 Regensburg > Phone: ++49-(0)941-944-5626 > Fax: ++49-(0)941-944-5632 > Email: justine.roc...@klinik.uni-regensburg.de > > > >>> Duncan Murdoch <murd...@stats.uwo.ca> 05.11.2009 12:36 >>> > On 05/11/2009 4:35 AM, Justine Rochon wrote: > > Dear R users, > > > > I would like to show the estimated density of a (0, 1) uniformly > distributed > > random variable. The density curve, however, goes beyond 0 and 1 because of > the > > kernel smoothing. > > > > Example: > > > > x = runif(10000) > > plot(density(x)) > > > > Is there a way to estimate the density curve strictly within (0, 1) and > still > > use some sort of smoothing? > > > > Any help would be greatly appreciated. > > One way is to extend the data by reflection on each end. That is, > > x <- runif(10000) > ex_x <- c(-x, x, 2-x) > den <- density(ex_x) > plot(den$x, 3*den$y, xlim=c(0,1), type="l") > > You need the rescaling to 3*den$y because you've tripled the range. > > Duncan Murdoch > > ______________________________________________ > 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. > > > -- Giovanni Petris <gpet...@uark.edu> Associate Professor Department of Mathematical Sciences University of Arkansas - Fayetteville, AR 72701 Ph: (479) 575-6324, 575-8630 (fax) http://definetti.uark.edu/~gpetris/ ______________________________________________ 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.
