[R] Apparent different in symbol scaling between xyplot and grid.points

[Sebastien Bihorel]

Thanks Baptiste,

I think you nailed it.

baptiste auguie wrote:
> Hi,
>
> I think the size mismatch occurs because of a different default for
> the fontsize (and grid.points has a size of 1 character by default).
> Compare the following two examples,
>
> # default
> grid.newpage()
> pushViewport(viewport(x=unit(0.5, "npc"), y=unit(0.5, "npc")))
> lplot.xy(data.frame(x=0.55,y=0.5),type="p", pch=3)
> grid.points(x=0.45,y=0.5, pch=3, gp=gpar(col="red"))
>
>
> trellis.par.set("fontsize", list(points=12))
>
> grid.newpage()
> pushViewport(viewport(x=unit(0.5, "npc"), y=unit(0.5, "npc")))
> lplot.xy(data.frame(x=0.55,y=0.5),type="p", pch=3)
> grid.points(x=0.45,y=0.5, pch=3, gp=gpar(col="red"))
>
> HTH,
>
> baptiste
>
> 2009/12/4 Sebastien Bihorel <Sebastien.Bihorel at cognigencorp.com>:
>   
>> Dear R-users,
>>
>> For the past few days, I have been trying to find the reason why some of my
>> plots were showing symbols of different sizes, while I thought I was using
>> the same .cex arguments everywhere. The problem is exemplified by the
>> following example code where the xyplot and grid.points functions are used.
>> The scaling factor is set to 0.84 in both the functions settings, but one
>> can see that, in the pdf file, the blue symbols plotted by xyplot are
>> smaller than the single black symbol created by grid.points. Playing with
>> the trellis settings did not seem to solve the problem. I am missing a
>> hidden scaling factor somewhere, but don't know where to look anymore
>>
>> I would greatly appreciate the feedback of the list on this issue.
>>
>> library(lattice)
>> library(grid)
>>
>> pdf(file="test.pdf")
>>
>> df <- data.frame(a=1:12,b=1:12,c=rep(1:4,each=3))
>>
>> #trellis.par.set(superpose.symbol=list(cex=1))
>>
>> xyplot(b~a|c,
>>      data=df,
>>      panel = function(x,y){
>>        panel.xyplot(x,y,pch=3,cex=0.84)}
>>      )
>>
>> str(trellis.par.get())      str(get.gpar())
>> grid.points(x=100,y=85,pch=3,gp=gpar(cex=0.84))
>>
>> dev.off()
>>
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>>
>>