Hi vod,

Now that I have your data I can do a bit better:

# save data as "vv.csv"

vv<-read.csv("vv.csv")

# order the points in order of theta

vv<-vv[order(vv$theta),]

oldpar<-polar.plot(vv$r,vv$theta,main="Polar plat of vv.csv",lwd=3,line.col=4,

point.symbols=4,rp.type="p",show.centroid=TRUE,radial.lim=c(0,max(vv$r)))

draw.circle(0.3,0.15,radius=2.5,lwd=2,border="red")

draw.ellipse(0.28,0.15,a=2.6,b=2.5,angle=19,border="green")

Using a circle (red) there is not much left to explain. Adjusting the

major and minor axes and the angle gives a pretty good fit.

Jim

On Wed, Dec 4, 2019 at 10:44 AM vod vos <

[hidden email]> wrote:

>

> Hi drjimlemon,

> Thank you, but it seems no working.

> The raw csv file is here, we need just consider the r and theta columns in polar coordinate.

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