[BioC] plot overlay

[David Ruau]

Hi,

I am trying to plot 2 plots in the same PDF.
The plot are 2 identical dendrograms except for the leave's label  
(some labels are empty). I would like to plot the first one in red and  
the second one in black. The idea I have is to use the second one as a  
mask hiding the red dendrogram on the common part.
 > class(dend1)
[1] "dendrogram"
 > class(dend2)
[1] "dendrogram"
##### Here the plot are merged but everything is red
 > pdf(file="color_dendrogram.pdf", height=100, width=400)
 > plot(dend2, col="red", panel.last=plot(dend1, col="black"))
 > dev.off()

##### Here the plot are merged but everything is black...
 > plot(dend2, panel.first=par(col="red"), panel.last=plot(dend1,  
panel.first=par(col="black")))

The final graph should be black (from dend1) and some of the label red  
(from dend2).

David
 > sessionInfo()
R version 2.7.0 (2008-04-22)
x86_64-unknown-linux-gnu

locale:
C

attached base packages:
[1] tools     stats     graphics  grDevices utils     datasets  methods
[8] base

other attached packages:
[1] lattice_0.17-6 bioDist_1.10.0 Biobase_2.0.1

loaded via a namespace (and not attached):
[1] grid_2.7.0