[R] 4 dimensional graphics

[jiho]

On 2008-January-10  , at 17:41 , Petr PIKAL wrote:
> Thank you
>
> Basically I have a rectangular space (like an aquarium) in which I  
> made
> some analysis.
> I can make
>
> image(lat, long, value) for each height but what I dream about is to  
> make
> something like scatterplot3d(lat, long, height) with points set  
> according
> to a value.
>
> Up to now i can do
>
> scatterplot3d(sloupecn, radan, vrstvan, color=as.numeric(cut(value,  
> c(0,
> 100, 400, 1000))))
>
> which will give you green and red points in upper right corner. I  
> started
> to try to make cex.symbols scaled according to value too but up to  
> now I
> did not manage to work correctly.
>
> in
>
> scatterplot3d(sloupecn, radan, vrstvan, cex.symbols = value/ 
> max(value)+2,
> color=as.numeric(cut(value, c(0, 100, 400, 1000))))
>
> the biggest points are at other places then I expected.

so you have measures at x,y,z points basically. and your measures  
appear to be on z layers so you can probably make several x,y plots  
with point size according to value, stacked on top of each other or  
side by side. one liner ggplots:

A=read.table("petr.txt",header=T)
library("ggplot2")
# stacked
ggplot(A,aes(x=x,y=y)) + geom_point(aes(size=value, colour=factor(z)))  
+ scale_size(to=c(0,10)) + scale_colour_hue(alpha=0.3)
# side by side
ggplot(A,aes(x=x,y=y)) + geom_point(aes(size=value)) +  
scale_size(to=c(0,10)) +facet_grid(z~.)

if you want 3d to explore your data, rgl (in which you can rotate  
plots etc) is probably the best choice

# 3D with rgl
library("rgl")
open3d()
spheres3d(A$x,A$y,A$z,A$value/1000)	
# NB. scaling your value is necessary since the values are so big  
compared to the coordinates
axes3d()

hope that helps.

petr.txt:

x y z value
1       4       1       73.8
1       4       9       54.9
1       4       17      72
1       1       1       96
1       1       9       52.1
1       1       17      53.3
4       4       1       58.4
4       4       9       93.5
4       4       17      140.2
4       1       1       90.3
4       1       9       36.5
4       1       17      55.1
7       4       1       169.1
7       4       9       718
7       4       17      813
7       1       1       73.4
7       1       9       46.5
7       1       17      205


JiHO
---
http://jo.irisson.free.fr/