baptiste Auguié <ba208 <at> exeter.ac.uk> writes: > > Dear list useRs,
You might be interested to apply the Hammersley or Halton point sets that are often used in numerical integration or Differential Evolution. These pseudo-random distributions are both uniform and irregular, but have a kind of minimum resolution There is an implementation of Halton Sequences in the often overlooked 'sfsmisc' package, see the 'QUnif()' function there. The help includes a visualization example dispaying the behavior I think you were looking for. Hans Werner > I have to generate a random set of coordinates (x,y) in [-1 ; 1]^2 > for say, N points. At each of these points is drawn a circle (later > on, an ellipse) of random size, [...] > > My problem is to avoid collisions (overlap, really) between the > points. I would like some random pattern, but with a minimum > exclusion distance. In looking up "Numerical recipes in C", I found > out about some Sobol quasi-random sequences, which one can call from > the gsl package, > [...] > but this does not look very random: I clearly see some pattern > (diagonals, etc...), and even the non-overlapping condition is not > impressive. > > One (painful) way I can foresee is to check the distance between each > symbol and the others, and move the overlapping ones in a recursive > manner. Before delving into this, I wanted to check I'm not > overlooking something in the rgl quasi-random sequences, or missing a > more obvious way to generate such patterns. Perhaps solving an > electrostatic problem with a potential both attractive at long > distances and repulsive at short distances is a better way? I have a > vague recollection of hearing that somewhere to position points > evenly on a sphere. > > Thanks for any comment / suggestion, > > Baptiste > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.