dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

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 <johan.hake@xxxxxxxxx> 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.

--
Anders



> I would do this in a separate script once for each mesh, and then save it to
> file so you do not have to do this each time you read in a mesh.



> Johan
>
> > > Johan
> >
> > Best regards
> > Neilen
> >
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