[R] Using panel.grid in barchart

[Christopher Jones]

Hi all,

I'm trying to do an example in Deepayan Sarkar's Lattice book.  It  
involves making a barchart based on the Titanic dataset.  I can get  
the barchart to plot fine; however, when I try to edit panel.grid, I  
get an error:

 > titan<-barchart(Class ~ Freq | Age + Sex, data =  
as.data.frame(Titanic), groups=Survived, stack=TRUE, layout=c(4,1),  
auto.key=list(title="Survived", columns=2), scales=list(x="free"))
 > titan     <--- this plot is fine
 > update(titan, panel = function(...) { panel.barchart(...)})  <--- 
same thing; also fine
 > update(titan, panel = function(...) { panel.grid(h = 0,v = -1)  
panel.barchart(...)})
Error: syntax error

Any advice?  I'm using R 2.8.1 on OS X Leopard if it helps.

Thanks,
Chris Jones
c_jones at mit.edu