Is something wrong wiht draw.circle()?

Hey R users,

I am a little bit confused.


require(plotrix)

plot(0,xlim=c(-10,10),ylim=c(-10,10),type="n",xlab="",ylab="")
draw.circle(0,0,5)

lines(c(0,0),c(0,5))
lines(c(0,5),c(0,0))

The culprit are unequal margins. Issue

par(mar = c(4,4,4,4))

before your code, and you will get a consistent circle.

More generally, when the scale of x axis and y axis are not the same
(i.e., 1 unit corresponds to different distances __on screen__),
drawing a naive circle would result in something that looks like an
ellipse on screen. Plotrix can apparently draw a real circle but then
the radius is "correct" only in the x direction.

HTH,

Peter