[R] mtext in trellis-loop & colorkey

[Marius Hofert]

Hello,

I would like to create a sequence of plots (using a for loop). I read  
in the FAQ that print() has to be used in order to obtain any output.  
This works perfectly fine as long as I only consider one function  
call in the loop, but I would like to add mtext() to the each plot in  
the loop. Unfortunately, this did not work. Any suggestions?

As you can see from the provided example, there is another problem  
with such animations: You do not see any difference in the plots  
(because only the "height" changes). Is there any possibility to keep  
a fixed scale for the colorkey (fixed labels and also fixed colors)  
and to see the different heights of the function from the colors  
(e.g. the first plot should be mainly gray (as it is the "lowest"),  
the last one mainly white (as it is the "highest")).

Thanks very much!

marius

Here is a complete minimal example:

remove(list=objects())
library(lattice)
for(i in 1:4){
	output_file_path<-paste("~/Desktop/test_",i,".png",sep="")
	x<-rep(seq(-3,3,length=50),50)
	y<-rep(seq(-3,3,length=50),each=50)
	z<-x*y+10*i
	trellis.device(png,color=F,file=output_file_path)
	print(wireframe 
(z~x*y,drape=T,distance=0,zoom=0.84,cuts=100,col.regions=gray 
(100:400/400),colorkey=list(tick.number=6)))
	#print(mtext(paste("Parameter= ",1,sep=""),side=3,line=0)) #This  
does not work!
	dev.off()
}