It sounds like you might want to draw the convex hull for each group of points. There is a package called "chplot" which appears to do this, though I haven't used it...
albyn On Thu, Jul 16, 2009 at 06:23:54PM +0100, Ahmed, Sadia wrote: > Hi, > > I'll try to keep my question brief and to the point, to anyone who helps > 'THANK YOU!' > > I want to get a circle/ring/buffer or some other form of drawn line around > certain points on a x,y plot, the points usually don't form a circle, often > they form a 'wobbly' shape, so ideally I'd like something that follows the > shape the points make. > > I'll start by explaining what I've got (I'm sorry if it's a little long, but > it's all important for explaining what I want to do): > > I have a simple 2D plot of an x variable, called 'percent.forest'', and a y > variable called 'metric'. the data for this plot is in a large data frame > with a third variable called 'Buffer', there are 5 buffer sizes (250, 500, > 1000, 3000, 10000). > > to create the plot I simply used > >plot(percent.forest,metric) > > to add in the data about buffer size, I have extracted the percent forest and > metric data by: > >buff250<-subset(data1,data1$Buffer==250) > >buff500<-subset(data1,data1$Buffer==500) > >buff1000<-subset(data1,data1$Buffer==1000) > >buff3000<-subset(data1,data1$Buffer==3000) > >buff10000<-subset(data1,data1$Buffer==10000) > > i then used the 'points' function to plot the percent forest, metric data > points in different colours according to buffer size, using this code (first > 2 lines divides the data appropriately, 3rd line is points): > >metric.250<-(log(buff250$metric)) > >percent.forest.250<-(buff250$percent.forest) > >points(percent.forest.250,metric.250,col='skyblue') > > I repeated this for all 5 buffer sizes, so on the plot > (percent.forest,metric) the points are coloured differently according to the > size of the buffer used. > This works fine (the next bit is the problem): > > Does anyone know how I can get R to draw around the different coloured > points, so that i get 5 rings/wiggly lines on the plot that clearly shows the > extent of each of the buffers, you can sort of see a pattern in the colours > but its not as clear as it would be if I could draw around it). > > If anyone wants to see a picture of the plot (if my explanation isn't clear > enough) I'd be happy to email one directly to you (the R instructions says > that the mailing list scraps attachments so I've not put one on here) > > Thank you for reading this, > Any help will be greatly appreciated, > sadia > > ______________________________________________ > 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.
