[R] what does "size" of a plotting character mean?

Prof Brian Ripley ripley at stats.ox.ac.uk
Thu Oct 4 11:44:43 CEST 2007

On Thu, 4 Oct 2007, Prasenjit Kapat wrote:

> Hi,
> plot(1,1, cex=2) means that the size of the plotting character (empty
> circle in this case) is double the default size. Now my question is:
> What characteristic of the symbol (circle) is double? Is it the area
> or the diameter?

Is it not obvious when you try it?  Diameter.

> What if the symbol is not a circle, what is the generic meaning of
> size in that case?

cex does linear scaling in each dimension.

There is no generic definition of what cex=1 means: it depends on the 
device, the font (for pch >=32 except ".") or the symbols (pch=1...25).

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)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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