Equivalent of box() in grid graphics

Hi

Paul Murell's article "What's in a Name" in The R Journal Vol 4/2
gives an interesting example of editing a stacked barplot of the barley
data.  Using the method described in that article, it's easy to do
something along the lines of

grid.edit("plot_01.border.strip.1",
           grep=TRUE, global=TRUE,
           gp=gpar(col = "red"))

That changes more than I'd like to change. I'd like to change only the
bottom line of the rectangle.  How would I overwrite the unwanted red
lines along the lines of what box() would do with base graphics?

You cannot modify just part of a basic shape (e.g., just the bottom line 
of a rectangle).  One way to do what I think you want is to specify a 
custom strip function that draws an extra line over the top of the 
existing rectangle, like this ...

library(lattice)
library(grid)
barchart(yield ~ variety | site, data = barley,
          groups = year, layout = c(1,6),
          stack = TRUE,
          ylab = "Barley Yield (bushels/acre)",
          scales = list(x = list(rot = 45)),
          strip = function(...) {
              strip.default(...)
              grid.segments(0, 0, 1, 0, gp=gpar(lwd=1.5, col="red"))
          })

Is that the sort of effect you want?

Paul

TIA
Patrick

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Dr Paul Murrell
Department of Statistics
The University of Auckland
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paul at stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/

|> Hi
|>

|> >Paul Murell's article "What's in a Name" in The R Journal Vol 4/2
|> >gives an interesting example of editing a stacked barplot of the barley
|> >data.  Using the method described in that article, it's easy to do
|> >something along the lines of
|> >
|> >grid.edit("plot_01.border.strip.1",
|> >           grep=TRUE, global=TRUE,
|> >           gp=gpar(col = "red"))
|> >
|> >That changes more than I'd like to change. I'd like to change only the
|> >bottom line of the rectangle.  How would I overwrite the unwanted red
|> >lines along the lines of what box() would do with base graphics?
|> 
|> You cannot modify just part of a basic shape (e.g., just the bottom
|> line of a rectangle).  One way to do what I think you want is to
|> specify a custom strip function that draws an extra line over the
|> top of the existing rectangle, like this ...
|> 
|> library(lattice)
|> library(grid)
|> barchart(yield ~ variety | site, data = barley,
|>          groups = year, layout = c(1,6),
|>          stack = TRUE,
|>          ylab = "Barley Yield (bushels/acre)",
|>          scales = list(x = list(rot = 45)),
|>          strip = function(...) {
|>              strip.default(...)
|>              grid.segments(0, 0, 1, 0, gp=gpar(lwd=1.5, col="red"))
|>          })
|> 
|> Is that the sort of effect you want?

I didn't really want thick red lines, but now that I know how to use
grid.segments, I can do what I need.

Thanks

~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.   
   ___    Patrick Connolly   
 {~._.~}                   Great minds discuss ideas    
 _( Y )_  	         Average minds discuss events 
(:_~*~_:)                  Small minds discuss people  
 (_)-(_)  	                      ..... Eleanor Roosevelt
	  
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.