Thanks! There are many points in our plot. I want to choose the points which distance to one point (e.g.(100,200)) is less than 10. And I want to draw a circle (radinus=10). The centre of the circle is the point (100,200). On 4/22/06, Gabor Csardi wrote: > > Hmmm, could you explain this a bit? > You want to add a circle to a plot? See the examples in help(symbols) > > Or you want to calculate the coordinates of the points on a circle? > > t <- seq(0,2*pi,length=100) > coords <- t(rbind( 10+sin(t)*2, 20+cos(t)*2)) > plot(coords) > > Here (10,20) is the center of the circle, and 2 is its radius. > If you set length to a bigger number you'll get smoother resolution. > > A points (x,y) is inside the circle if (c1-x)^2+(c2-y)^2 < r^2 > (c1, c2) is the center of the circle, r is its radius. > > Gabor > > On Sat, Apr 22, 2006 at 01:42:46PM -0400, Jian Zhang wrote: > > how to draw a circle (e.g. radius=10cm) of one point? > > And how to choose these points in the circle? > > Thanks! > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@stat.math.ethz.ch mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > -- > Csardi Gabor MTA RMKI, ELTE TTK > [[alternative HTML version deleted]]