[MOAB-dev] h5m with data

[Patrick Shriwise]

Hey Nico,

Ok. There doesn't appear to be a great example for applying data. 
Applying data works in a very similar way to the way you retrieve tagged 
data, using tag_set_data with a Tag which can be created for a certain 
type of data with a given name by calling tag_get_handle with the 
MBCREAT option at the end. I'd like to be clear that you can 
apply/retrieve data from MOAB Entities or MOAB EntitySets. So you can 
either apply data directly to entities like vertices or you can group 
them together in a set and apply data to that set instead. For the 
purpose you're indicating, it sounds like it'd be best to apply the data 
directly to the vertices.

Sample code for creating a MOAB Tag:
   Tag name_tag;
   rval = mdbImpl->tag_get_handle(NAME_TAG_NAME, NAME_TAG_SIZE, 
MB_TYPE_OPAQUE,
                                  name_tag, MB_TAG_SPARSE | MB_TAG_CREAT);
Cheers,

Patrick C. Shriwise
Research Fellow
University of Wisconsin - Madison
Engineering Research Building - Rm. 428
1500 Engineering Drive
Madison, WI 53706
(608) 446-8173

On 11/08/15 21:01, Nico Schlömer wrote:
> In both ways, actually. I need to build h5m files from data and I need 
> to extract data from h5m meshes.
> With [1], I'm digging my way through understanding the sets group now.
>
> --Nico
>
> [1] https://trac.mcs.anl.gov/projects/ITAPS/wiki/MOAB/h5m
>
> On Mon, Nov 9, 2015 at 2:53 AM Patrick Shriwise <shriwise at wisc.edu 
> <mailto:shriwise at wisc.edu>> wrote:
>
>     Hi Nico,
>
>     I see. I may have misunderstood your problem. It seems you're
>     trying to apply data to the mesh. Is that right?
>
>
>     Cheers,
>
>     Patrick C. Shriwise
>     Research Fellow
>     University of Wisconsin - Madison
>     Engineering Research Building - Rm. 428
>     1500 Engineering Drive
>     Madison, WI 53706
>     (608) 446-8173
>
>     On 11/08/15 20:03, Nico Schlömer wrote:
>>     Thanks Patrick for your reply.
>>
>>     I'm still having problems where data should be stores. In a h5m
>>     file, I see tags, I see sets with tags in them, and it seems they
>>     are somehow related, but I don't know where and how to put the
>>     actual data. I would help to see a file with some mesh and a
>>     custom data element in it, e.g., an array of values associated
>>     with the vertices.
>>
>>     Cheers,
>>     Nico
>>
>>     On Sun, Nov 8, 2015 at 9:20 PM Patrick Shriwise
>>     <shriwise at wisc.edu <mailto:shriwise at wisc.edu>> wrote:
>>
>>         Hi Nico,
>>
>>         The vertex data should be stored in MOAB tags. You can access
>>         these tags via their name. There is a set of conventions for
>>         the tag names in an Exodus file (here
>>         <http://ftp.mcs.anl.gov/pub/fathom/moab-docs/MBTagConventions_8hpp.html>
>>         I think). However, if the tag has a custom name and isn't
>>         recognized by the Exodus reader, then the data might not be
>>         read in from the Exodus file and as a result won't be saved
>>         into the .h5m. Do you have an idea of what the tag name might
>>         be for your data?
>>
>>         There's also a good example here
>>         <http://ftp.mcs.anl.gov/pub/fathom/moab-docs/SetsNTags_8cpp-example.html>
>>         of how to access the tag data on an entity. The example I
>>         linked you to accesses EntitySets rather than Entities, but
>>         they work the same way.
>>
>>         If you think the data might be in the .h5m, you can use
>>         tag_get_tags_on_entity
>>         <http://ftp.mcs.anl.gov/pub/fathom/moab-docs/classmoab_1_1Interface.html#a6c737e7900d9c1b29b53d994076d204f>
>>         to get all of the tags on a vertex and then check for the tag
>>         data you're looking for. An easier way of doing this in the
>>         cmd line is by using mbsize -t <your_file>.h5m to print out
>>         the count by tag.
>>
>>         Hope this helps!
>>
>>         Cheers,
>>
>>         Patrick C. Shriwise
>>         Research Fellow
>>         University of Wisconsin - Madison
>>         Engineering Research Building - Rm. 428
>>         1500 Engineering Drive
>>         Madison, WI 53706
>>         (608) 446-8173
>>
>>         On 11/08/15 13:43, Nico Schlömer wrote:
>>>         Hi everyone,
>>>
>>>         I have an Exodus file with vertex data in it (i.e., "a
>>>         function" defined on the vertices). When converting this
>>>         file to h5m, where does the vertex data go? And how to I
>>>         retrieve the data after having it read with `load_file()`?
>>>
>>>         Cheers,
>>>         Nico
>>
>

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