[R] drawing a circle using symbols

Paul Murrell p.murrell at auckland.ac.nz
Tue Nov 29 20:05:29 CET 2005


Troels Ring wrote:
> Dear friends, I was drawing a circle with centrum in (1,-1) and 
> radius 5 to show my girl that the line y=3*x+1 goes through (1,4) and 
> (-2,-5) of the circle, but on Windows XP, R 2.20 the drawing was not 
> good at all, and the known solutions were not shown in the graph. I 
> guess I got it wrong? Is this use not intended ?
> Best wishes
> Troels Ring, MD
> Aalborg, Denmark
> symbols(x=1,y=-1,circles=5,inches=FALSE, xlim=c(-10,10),ylim=c(-10,10))
> curve(3*x+1,-10,10,1000,add=T)
> abline(v=c(-2,1))
> abline(h=c(-1,-5,4))

The important part may be that your plot is not square.   In the help 
file for symbols() it says (NOTE the "x axis") ...

   inches: If 'inches' is 'FALSE', the units are taken to be those of
           the x axis.

If you precede your code with ...


... does the result look better?

Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
New Zealand
64 9 3737599 x85392
paul at stat.auckland.ac.nz

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