On Sat, 11 Feb 2006, Roger Bivand wrote: > On Sat, 11 Feb 2006, mark shanks wrote: > >> I have a set of data in x,y coordinates across the range of -5 to 5 in each >> dimension. I would like to obtain the frequency distribution of the >> different points, and then graph them so you can see which of the points are >> the most frequently occurring. >> >> This would seem to be easy in Matlab, which has the hist3 command for doing >> frequency distributions/histograms in 3 dimensions. However, as far as I can >> tell, R does not have a hist3 command. > > See contributed package ash, function bin2: > >> xy <- cbind(x=runif(250,-5,5), y=runif(250,-5,5)) >> bins <- bin2(xy, ab=matrix(c(-5,-5,5,5),2,2)) >> image(bins$nc) > > or > >> filled.contour(bins$nc) > > Using the x and y arguments to image or filled.contour, you can set the > axes, and asp=1 to preserve aspect. > > See also function kde2d in package MASS - included in the standard > distribution.
And density plots are usually a lot better than histograms for understanding 2D data. > IMO, 3D histograms can mislead because perception depends on viewer > position. All of the above give readily interpreted visualisations based > on colour class intervals. But if you really want one, see demo("hist3d") in package rgl, which allows you to change your position interactively and uses translucency. >> Is there any easy way to do this in R? I'm investigating whether matlab or R >> is more suitable for our needs, but don't want to reject R due to my present >> ignorance of its functions. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html