speed up "remove_faces" for simplicial complexes

[jhpalmieri]

The attached patch, taken from a discussion on ask.sagemath.org, speeds up remove_face for large simplicial complexes. For smaller ones, it is comparable, perhaps a little slower, but the speed-up for large ones is significant.

Before the patch:

sage: S = range(1,8)
sage: timeit('Z = SimplicialComplex(S, [S]); Z.remove_face([1,2,3])')
625 loops, best of 3: 767 µs per loop

sage: timeit('SimplicialComplex(10,[[0,1,2,3,4,5,6],[1,2,3,4,5,6,7],[0,1,2,4,5,6,7],[0,1,2,3,5,6,7],[0,1,2,3,4,5,7]]).remove_face(Simplex([1,2,5]))')
5 loops, best of 3: 42.2 ms per loop

After the patch:

sage: S = range(1,8)
sage: timeit('Z = SimplicialComplex(S, [S]); Z.remove_face([1,2,3])')
625 loops, best of 3: 835 µs per loop

sage: timeit('SimplicialComplex(10,[[0,1,2,3,4,5,6],[1,2,3,4,5,6,7],[0,1,2,4,5,6,7],[0,1,2,3,5,6,7],[0,1,2,3,4,5,7]]).remove_face2(Simplex([1,2,5]))')
125 loops, best of 3: 1.79 ms per loop

The original idea (from ask.sagemath.org) is by "EmersonL", and John Palmieri modified it and wrote the actual patch.

Component: algebraic topology

Keywords: simplicial remove_face

Author: John Palmieri

Reviewer: Mike Hansen

Merged: sage-5.0.beta14

Issue created by migration from https://trac.sagemath.org/ticket/11625

[mwhansen]

Reviewer: Mike Hansen

[mwhansen]

comment:2

Attachment: trac_11625-remove-face.patch.gz

Looks good to me.

[jdemeyer]

Merged: sage-5.0.beta14