On Mon, Mar 14, 2011 at 10:31:21AM -0700, Johan Hake wrote: > On Monday March 14 2011 10:25:10 Anders Logg wrote: > > On Mon, Mar 14, 2011 at 09:06:00AM -0700, Johan Hake wrote: > > > On Monday March 14 2011 08:44:19 Neilen Marais wrote: > > > > Johan, > > > > > > > > On Mon, Mar 14, 2011 at 5:21 PM, Johan Hake <[email protected]> > wrote: > > > > > On Monday March 14 2011 04:36:29 Neilen Marais wrote: > > > > > If you have an already tetrahedralized structure, typically given by > > > > > a coordinate array and an array of conductivities between cells and > > > > > vertices, you can use MeshEditor. That is what MeshEditor really is > > > > > for. > > > > > > > > > > > > > > > I think the advice of not using MeshEditor is when you use it to > > > > > construct the vertices and connectivities by hand. > > > > > > > > I guess I'm just worrying about performance in python, since I would > > > > have to do one method call for each vertex and one for each tet. I may > > > > be prematurely optimising here, but IIRC even method calls to SWIG > > > > wrapped C++ classes have a fair amount of overhead. Since I already > > > > have the vertex coordinates and cell -> vertex connectivity data in > > > > arrays, it is obviously much faster to just stuff them directly into > > > > the dolfin structures? > > > > > > Sure you are right that it might come with some overhead. Not sure it > > > will be significant though, as this would probably be a one time thing? > > > > > > But after reading your post one more time I realize what you asked for > > > :P, and the answer is yes! You can perfectly do what you did. > > > mesh.cells() and mesh.coordinates() each return a NumPy array view of > > > the actuall data. Your syntax works because NumPy allows it. > > > > It works because it happens to work. It's not intended usage and it > > might break if we change the implementation MeshEditor, even if the > > interface stays the same. > > > > It would be better to add some utility function for creating a Mesh > > based on arrays. > > I agree. > > But as long as we store the coordinates and cells as contiguous arrays in the > mesh, they will be exposed to Python through NumPy and this will just work.
Not necessarily. The MeshEditor might postpone initializing the arrays until it has received all calls to add_cell etc and only then allocate the arrays. So the mixing of MeshEditor.open, close and array access only works if it is compatible with what MeshEditor does internally. -- Anders _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : [email protected] Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
