[R] Need frequency distribution for x,y coordinates

[Jim Lemon]

mark shanks wrote:
 >
 > Hi,
 >
 > 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.

If a 2D display is okay, you can use the color2D.matplot function in the 
plotrix package to plot the output of something like kde2d in MASS:

x<-seq(-5,5,by=0.1)
xdens<-kde2d(sample(x,500,TRUE),sample(x,500,TRUE),n=11)
color2D.matplot(xdens$z,c(1,0),c(0,1),c(0,0),
show.legend=TRUE,xlab="Columns",ylab="Rows")

Jim