[R] circle / oval / semicircle ?

[Prof Brian Ripley]

Circles *are* a graphics primitive in the sense that every R device driver
has to support them.  See PS_Circle and PDF_Circle in file
src/main/devPS.c Note that PDF does not have arcs/circle as a primitive,
unlike PS.

One gotcha is that you have to be able to draw circles clipped to a 
viewport.

OTOH, adding a graphic primitive (and we seem to need image for e.g. 
better drawing of the output of image and for icons etc) is a very serious 
undertaking.

The R interfaces are symbols() and grid.circle.


On Fri, 25 Jun 2004, ivo welch wrote:


> thanks, guys.  circles might be a good candidate for a graphics 
> primitive in the next R version, if only because---unlike the solutions 
> here---I believe that postscript/pdf have scaleable primitives---though 
> I am no postscript expert.  of course, if I knew what I was talking 
> about, I would just write the function and submit it.  the closest I 
> have found was in http://wtonline.vitalnews.com/Pages/Tip0163.html

-- 
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