Problems drawing a colored 'rug' in the Lattice 'densityplot'

Mark -
   If I understand what you want, it can be done with a custom
panel function:

mypanel = function(x,subscripts,groups,...){
  
panel.densityplot(x,plot.points=FALSE,groups=groups,subscripts=subscripts,...) 

  
panel.rug(x,col=trellis.par.get('superpose.line')$col[groups[subscripts]]) 

}

Then I think you'll get the result you want if you use

densityplot(~Value|Type, group=Category, data=d, panel=mypanel)

                    - Phil Spector
                     Statistical Computing Facility
                     Department of Statistics
                     UC Berkeley
                     spector at stat.berkeley.edu

On Thu, 16 Dec 2010, Mark Dalphin wrote:

Hi All,

I'm trying to add a 'rug' representation of my data to a plot created 
with densityplot(). While I can do this in the simple case, I can't 
do it properly when I include the "groups" argument. I have an 
example below. I am running a reasonably new version of R.

print(sessionInfo())
R version 2.12.0 Patched (2010-11-07 r53537)
Platform: i686-pc-linux-gnu (32-bit)

locale:
[1] LC_CTYPE=en_NZ.UTF-8       LC_NUMERIC=C               
LC_TIME=en_NZ.UTF-8 LC_COLLATE=en_NZ.UTF-8    [5] LC_MONETARY=C 
LC_MESSAGES=en_NZ.UTF-8    LC_PAPER=en_NZ.UTF-8       LC_NAME=C [9] 
LC_ADDRESS=C               LC_TELEPHONE=C LC_MEASUREMENT=en_NZ.UTF-8 
LC_IDENTIFICATION=C attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base 
other attached packages:
[1] lattice_0.19-13

R code to show the problem:

## Setup - load package, set random seed & create fake dataset
library(lattice)
set.seed(1234)
d <- data.frame(Type=rep(LETTERS[1:4], times=250),
              Category=rep(LETTERS[22:26], times=200),
              Value=c(rnorm(500), rnorm(300, 0.5), rnorm(200, 1))
              )

## Basic "densityplot" using 'points' to show the data
densityplot(~Value|Type, data=d)

## And I can plot a 'rug' for the simple density plot
densityplot(~Value|Type, data=d, plot.points='rug')

## Now add a "groups" selector to show sub-grouping of data by 
'Category'
## Note: the data points are in color
densityplot(~Value|Type, group=Category, data=d)

## Finally, with the groups, and with a rug.
## Note: no color for the rug
densityplot(~Value|Type, group=Category, data=d, plot.points='rug')


So, I can draw a rug (which is an improvement over version 2.9.1 of R 
when I got no rug), however, the color associated with the 'group' 
doesn't seem to propagate through to the rug. Is there something I am 
doing wrong here or is this a bug? Anyone have suggestions to work 
around this?

Regards,
Mark
--