[MOAB-dev] get uniquely owned vertices

[Vijay S. Mahadevan]

> So both `get_entities_by_dimension` and `get_shared_entities`  return owned
> and ghosted entities?

Yes. The interface routines have no idea about the domain
decomposition. So they return whatever entities match your query, from
the set that is locally visible (which typically is
owned+shared/interface+ghosted).

Vijay

On Mon, Dec 7, 2015 at 8:45 AM, Nico Schlömer <nico.schloemer at gmail.com> wrote:
> Thanks Vijay for the explanation.
> So both `get_entities_by_dimension` and `get_shared_entities`  return owned
> and ghosted entities?
>
> Cheers,
> Nico
>
> On Mon, Dec 7, 2015 at 2:31 PM Vijay S. Mahadevan <vijay.m at gmail.com> wrote:
>>
>> Hi Nico,
>>
>> You can use pstatus tag to filter out [1] your desired entities once
>> you have a superset of entities you care about. All calls on MOAB
>> Core/Interface return matching entities that are local (owned + shared
>> + ghosted) only. So if you want only owned entities, or only ghosted
>> ones, you can do something like this:
>> ```
>>   moab::Range allverts, ownverts, ghostverts;
>>   ierr = mb->get_entities_by_dimension(0, 0, allverts);
>>   ierr = pcomm->filter_pstatus(allverts, PSTATUS_NOT_OWNED,
>> PSTATUS_NOT, -1, &ownverts);
>>   ierr = pcomm->filter_pstatus(allverts, PSTATUS_GHOST, PSTATUS_OR,
>> -1, &ghostverts);
>> ```
>>
>> Vijay
>>
>> [1]
>> ftp://ftp.mcs.anl.gov/pub/fathom/moab-docs/classmoab_1_1ParallelComm.html#ad151b3b024cfd0ab7adc00f77e2551c2
>>
>> On Mon, Dec 7, 2015 at 6:25 AM, Nico Schlömer <nico.schloemer at gmail.com>
>> wrote:
>> > Hi everyone,
>> >
>> > When reading a mesh in parallel, I would like to get the vertices such
>> > that
>> > every vertex belong to exactly one process. When reading with
>> > ```
>> >   moab::Range verts;
>> >   ierr = mb->get_entities_by_dimension(0, 0, verts);
>> > ```
>> > the vertices along the process interfaces will be shared, i.e., they
>> > appear
>> > on two processes.
>> >
>> > I used to believe the above does the right thing and I have to use get
>> > the
>> > shared entities separately
>> > ```
>> >   moab::Range shared;
>> >   ierr = mcomm_->get_shared_entities(-1, shared, 0);
>> >   all.merge(shared);
>> > ```
>> > but it seems I'm on the wrong track.
>> >
>> > Any hints?
>> >
>> > Cheers,
>> > Nico