[R] Dotplot (package Hmisc) with groups: colours and symbols

[Peter Ehlers]

On 2011-05-11 02:11, E Hofstadler wrote:
> Hello all,
>
> This question concerns the function Dotplot from the Hmisc package.
>
> My aim is to compare values between groups in each panel of the
> Dotplot, with the values of different groups clearly distinguishable
> by different symbols. All lines and symbols should be coloured in
> black.
>
> Before adding the panel function to the Dotplot, the groups behaved as
> desired and were marked by different symbols, but the error bands were
> blue instead of black. After adding the panel function and changing
> the trellis colour settings, the error bars are now black, but now the
> groups are suddenly marked by the same rather than different symbols.
> I've tried several ways to change the group symbols but to no avail.
>
> ## set CI lines to black
> t1 = trellis.par.get("plot.line")
> t1$col<- "black"
> trellis.par.set("plot.line",t1)
>
> ## load example data
> require(lattice)
> data(barley)
>
> ## example plot (problem: groups marked by the same symbol)
>
> require(Hmisc)
> Dotplot(site~Cbind(yield, yield+5, yield-5)|variety, groups=year,
> data=barley, pch=c(1,2), col="black",
>          panel=function(x,y){
>              panel.Dotplot(x,y,col="black")})
> Key()
>
>
>
>
> What am I doing wrong?

It seems to me that 'plot.line' is the wrong lattice parameter to set.
Try this:

  Dotplot(site~Cbind(yield, yield+5, yield-5)|variety, groups=year,
   par.settings=list(superpose.line=list(col="black")),
   data=barley, pch=c(1,2), col="black")

No need to specify the panel function. (To see what's wrong with
the panel function, add '...' to the arguments.)

Peter Ehlers

>
> Many thanks in advance.
> Esther
>
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