R help - Mar 2011 - How does the cex parameter scale circles?

I'm wondering how the cex parameter is used to scale circles (i.e. does it
scale the radius, diameter, area, circumference, etc.?). In my case I'm
using lattice with filled circles (pch=19).
 
Based on example, it looks like R scales the radius of the circle:
 
library(lattice)
dta<-data.frame(x=rep(1,6),y=rep(1,6),sz=c(1,2,4,8,16,32))
xyplot(x~y,data=dta,col=rgb(0,0,0,50,maxColorValue=255),cex=dta$sz,pch=19)
 
But I haven't been able to find confirmation in any R documentation, so any
assistance would be much appreciated. Cheers.
	[[alternative HTML version deleted]]

'cex' means character expansion.  It is linear magnification: that is 
all linear dimensions (including height and width) are proportional to 
cex).

You are confusing matters by giving a lattice example.  'cex' is a 
concept from base graphics (see ?par, which I believe is unambiguous 
in saying it is a magnification), but lattice is built on grid.  And 
?grid::gpar says

        cex         Multiplier applied to fontsize


On Wed, 9 Mar 2011, Al Roark wrote:
> I'm wondering how the cex parameter is used to scale circles (i.e. 
> does it scale the radius, diameter, area, circumference, etc.?). In 
> my case I'm using lattice with filled circles (pch=19).
>
> Based on example, it looks like R scales the radius of the circle:
>
> library(lattice)
> dta<-data.frame(x=rep(1,6),y=rep(1,6),sz=c(1,2,4,8,16,32))
> xyplot(x~y,data=dta,col=rgb(0,0,0,50,maxColorValue=255),cex=dta$sz,pch=19)
>
> But I haven't been able to find confirmation in any R documentation, 
> so any assistance would be much appreciated. Cheers.
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
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>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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