Re: Simple graph question - drawing circles

[hurley.gj@pg.com]

I recently wrote such a function.  The trick is to figure out where to place unit circles on a grid to have the overlaps you want.  There an example of plotting a unit circle in the S-Plus 6 programmers guide manual, p.302:

unit.circle<-complex(argument=seq(from=-pi, to= pi, length=20))
plot(unit.circle)

This only gives 20 points though.

The following gives three circles that I think make a reasonable Venn diagram.  Just use 

These three circles are in positions where I liked them
circ1<-complex(argument=seq(-pi,pi,0.0005))-complex(real=0.5,imaginary=-(sqrt(3)/2))
circ2<-complex(argument=seq(-pi,pi,0.0005))+complex(real=0.5,imaginary=(sqrt(3)/2))
circ3<-complex(argument=seq(-pi,pi,0.0005))+complex(real=0,imaginary=2)
points(circ1)
points(circ2)
points(circ3)

Use text, mtext, par, etc. to do what you want with them.....


-George.


George J. Hurley
The Procter and Gamble Company
Miami Valley Innovation Center, Box 30
11810 East Miami River Road
Cincinnati, OH 45252
(513) 627-0692

"Walter R. Paczkowski" <dataanalytics@earthlink.net> Sent by: s-news-owner@lists.biostat.wustl.edu 02/14/2005 03:42 PM

To:        "S-News" <s-news@lists.biostat.wustl.edu>         cc:        (bcc: George Hurley-GJ/PGI)         Subject:        [S] Simple graph question - drawing circles

Hi,

Does anyone know a simple function to draw three overlapping circles as in a Venn Diagram?  I want to draw three circles, have all edges of the circles visible (as if I'm drawing on a chalkboard), and then be able to place labels in the 7 interior parts (the overlaps).

Any suggestions are appreciated.

Thanks,

Walt Paczkowski

________________________

Walter R. Paczkowski, Ph.D.
Data Analytics Corp.
44 Hamilton Lane
Plainsboro, NJ  08536
(V) 609-936-8999
(F) 609-936-3733

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