[R] How does the cex parameter scale circles?

[Prof Brian Ripley]

'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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