Hi Nathan, This only fits some of your criteria, but have you looked at ?stat_density2d?
Best, Ista On Mon, Jan 28, 2013 at 12:53 PM, Nathan Miller <natemille...@gmail.com> wrote: > Hi all, > > I have been looking for means of add a contour around some points in a > scatterplot as a means of representing the center of density for of the > data. I'm imagining something like a 95% confidence estimate drawn around > the data. > > So far I have found some code for drawing polygons around the data. These > look nice, but in some cases the polygons are strongly influenced by > outlying points. Does anyone have a thought on how to draw a contour which > is more along the lines of a 95% confidence space? > > I have provided a working example below to illustrate the drawing of the > polygons. As I said I would rather have three "ovals"/95% contours drawn > around the points by "level" to capture the different density distributions > without the visualization being heavily influenced by outliers. > > I have looked into the code provided here from Hadley > https://groups.google.com/forum/?fromgroups=#!topic/ggplot2/85q4SQ9q3V8 > using the mvtnorm package and the dmvnorm function, but haven't been able > to get it work for my data example. The calculated densities are always > zero (at this step of Hadley's code: dgrid$dens <- > dmvnorm(as.matrix(dgrid), ex_mu, ex_sigma) ) > > I appreciate any assistance. > > Thanks, > Nate > > x<-c(seq(0.15,0.4,length.out=30),seq(0.2,0.6,length.out=30), > seq(0.4,0.6,length.out=30)) > y<-c(0.55,x[1:29]+0.2*rnorm(29,0.4,0.3),x[31:60]*rnorm(30,0.3,0.1),x[61:90]*rnorm(30,0.4,0.25)) > data<-data.frame(level=c(rep(1, 30),rep(2,30), rep(3,30)), x=x,y=y) > > > find_hull <- function(data) data[chull(data$x, data$y), ] > hulls <- ddply(data, .(level), find_hull) > > fig1 <- ggplot(data=data, aes(x, y, colour=(factor(level)), > fill=level))+geom_point() > fig1 <- fig1 + geom_polygon(data=hulls, alpha=.2) > fig1 > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.
