On Sun, Oct 27, 2013 at 6:28 PM, Freddie Witherden <[email protected]> wrote: > Hi all, > > This is a question which has been bugging me for a while. I have an (N, > 3) array where N ~ 16 of points. These points are all unique and > separated by a reasonable distance. > > I wish to sort these points into a canonical order in a fashion which is > robust against small perturbations. In other words changing any > component of any of the points by an epsilon ~ 1e-12 should not affect > the resulting sorted order.
I don't understand how this is possible even in principle. Say your points are a = [0, 0, 0] b = [0, 0, 1e-12] According to your criterion, either a or b should go first -- I don't know which. Let's say our canonical ordering decides that a goes first. But if you perturb both of them, then you have a = [0, 0, 1e-12] b = [0, 0, 0] And now your requirement says that a still has to go first. But if a goes first this time, then b had to go first the last time, by symmetry. Thus your criterion is self-contradictory...? -n _______________________________________________ NumPy-Discussion mailing list [email protected] http://mail.scipy.org/mailman/listinfo/numpy-discussion
