On 14-Jun-04 Luca Scrucca wrote: > Dear R-users, > > Suppose I have the following x-y coordinates which give the > boundaries of a polygon: >> x <- c(5,4,5,9,6,6,4,7,10,7,10,4,10) >> y <- c(6,3,2,6,3,7,5,4,4,7, 5,4, 6) > > I would like to plot the following graph: >> plot(x,y) >> ord <- c(7,12,2,3,5,8,9,11,13,4,10,6,1) >> polygon(x[ord],y[ord]) > > How I can obtain the above ordering (in the example an anti-clockwise > ordering) such that I can use polygon() to connect the points? > > I searched previous messages but I did not find any relevant to this > problem.
I don't think your problem is well specified! It looks as though you want to draw a polygon, such that the edges linking successive vertices do not intersect (and. as it happens, "anticlockwise"). However, your vertices above do not give a unique solution if the problem is stated in this way. For instance (just looking at the plot) there are the following (and others): 1 7 12 2 3 5 8 9 11 13 4 10 6 1 (the most "natural" order, perhaps) 1 7 12 8 2 3 5 9 11 4 13 10 6 1 1 7 12 2 8 5 3 9 11 13 4 10 6 1 So what more do you need to state, to make the solution unique? Best wishes, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <[EMAIL PROTECTED]> Fax-to-email: +44 (0)870 167 1972 Date: 14-Jun-04 Time: 11:31:55 ------------------------------ XFMail ------------------------------ ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
