[R] lattice color problem with symbols: bug?

[Sundar Dorai-Raj]

Stefan Grosse said the following on 1/11/2008 10:04 AM:
> Dear useR's,
> 
> I have a problem with the lattice plotting of some symbols:
> 
> library(lattice)
> 
> test<-data.frame(x=c(2,3,1,5),u=c(rep(1,2),rep(2,2)),g=c(rep(c(1,2),2)))
> 
> xyplot(x~u,groups=g,
>  data=test,
>  par.settings=list(
>     superpose.symbol=list(pch=c(22, 23),cex=c(1.7,1.6),col="black")
>     ),
>  key=list(
>     text=list(c("t1","t2")),
>     space = "bottom",pch=c(23, 22),
>     points=F,
>     cex=1.0,
>     col="black"
>     ),
> )
> 
> As you see the symbols which have been plotted into the plotting area appear 
> to have some filling color while in the legend there is no filling color 
> although the specification of the symbols is the same.
> 
> If I use a normal plot command, the symbols are also not filled:
> plot(c(1,2,3),c(1,2,3),pch=c(22,23,24),cex=1.5)
> 
> That problem must have occured during a recent lattice update since the color 
> was not there when I was plotting a year ago with R2.5.x and some older 
> lattice. It occurs on my linux as well as on my windows machine both with R 
> 2.6.1 and latest lattice from CRAN.
> 
> So here my questions: How do I get rid of the color? (or is it a bug?) If it 
> is a feature, so how do I determine the color in both the symbols in the 
> legend and in the plot itself? (Actually I was overlaying two plots e.g. one 
> colored diamond and one empty diamond to achieve that effect but if there is 
> a more efficient way to draw bordered symbols with customized color that 
> would be preferable...)
> 
> Stefan
> 

Hi, Stefan

You need to use "fill = 'transparent'" in your par.settings call. If 
you're not using a fill color, you probably should use pch = c(0, 5) 
instead. This is explained under pch on the ?points help page.

Here's a modified version of your example:

library(lattice)
test <- data.frame(x = c(2, 3, 1, 5),
                    u = rep(1:2, each = 2),
                    g = paste("t", rep(1:2, 2), sep = ""))

xyplot(x ~ u, data = test, groups = g,
        par.settings = list(
          superpose.symbol = list(
            pch = c(22, 23),
            cex = c(1.7, 1.6),
            fill = c("red", "blue"),
            col = "black")),
        auto.key = list(space = "bottom"))

HTH,

--sundar