[Dune] reading multiple tags with GmshReader

Oliver Sander sander at igpm.rwth-aachen.de
Fri Jun 19 07:40:02 CEST 2015

Am 18.06.2015 um 20:56 schrieb Christian Engwer:
> Dear Ganesh,
> sadly in the current state none of this works. Oli recently removed
> the half-implement reader for more than one tag, as it was never
> finished. Reading other things than elements or boundary elements is
> currently not possible.
> In the issue you reference, nobody ever offered a patch and further
> more the author never replied to my questions.
> But perhaps you can answer some of them:
> * Which information can be added as a tag. Is this restricted to int,
>   or can it be arbitrary data, e.g. double values?

As I understand the spec, and element can have an arbitrary positive number of
integer tags.

> * Is it only possible to use additional tags for cells, or also for
>   boundary entries? Reading your comment below I guess there is also
>   some way to add tags to other entities!?

Yes, that is possible.  The boundarySegmentToPhysicalEntity field actually
returns the first tag of each codim-1 entity.

> and which program can I use to generate such files? My Gmsh
> installation only uses the physical entity tag.
> If you are interested in providing patches, I'll happily guide you
> through the code to implement the missing features. Reagrding the
> cells should be fairly simple once we know what type of data can be
> attached. We basically have to revert Olis recent patch and add an
> additional constructor which takes more than one vector. 

Maybe we can think a little before adding a new constructor.  Just adding
another vector argument still does not cover all the generality of the
file format.

>> partition info tags as well. Additionally, is there a way to extract the
>> tags (physical, geometry and partition) for the edge-element (denoted by a
>> type 1 element in Gmsh, eg. a 2-noded edge of a 4-noded quadrilateral) as
>> well?

The 'physical' for edge elements are returned in the boundarySegmentToPhysicalEntity


>> I see that this issue was considered before (FS#935) but I do not know if
>> it was resolved and a patch was applied.
>> Ganesh
>> _______________________________________________
>> Dune mailing list
>> Dune at dune-project.org
>> http://lists.dune-project.org/mailman/listinfo/dune

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