How to compute the convex hull of a set of points in the plane?
How to compute the convex hull of a set of points in the plane and obtain the resulting vertices as a list in the good order?
The following does not work because the vertices are returned in any order. You can confirm this by drawing the polygon of them.
sage: p = Polyhedron(vertices = [(random(),random()) for _ in range(10)]) sage: p.vertices() (A vertex at (0.02426982921, 0.8569166506), A vertex at (0.9906153404, 0.5055452233), A vertex at (0.8056807969, 0.9885901971), A vertex at (0.02148155632, 0.6201313201), A vertex at (0.8789116179, 0.4107095649), A vertex at (0.1045180727, 0.2367290111)) sage: polygon(p.vertices())
p.plot() does show the polyhedra correctly, so I found the following method to get the list I want :
sage: good = p.plot()._objects[-1] sage: good Polygon defined by 6 points sage: I_want_this_list = zip(good.xdata, good.ydata) sage: polygon(I_want_this_list)
There should be a cleaner way to get my list no? In general, the polygon might not be stored in the last item of the list