[petsc-users] storing many petsc objects in a single file

[Matthew Knepley]

On Mon, Nov 27, 2017 at 2:46 PM, Storm Weiner <stormweiner at berkeley.edu>
wrote:

> Thanks for the advice.
>
> Barry,  did you mean to add more information after that ":"?
>
> HDF5 sounds like a great option for my application,  but I don't see much
> information about how it interfaces with PETSc.   All I can find are the
> doc pages for a few viewer routines.  Do you have a link to a more detailed
> description?
>
> Specifically,  I'd like to know if PETSc has automatically configured HDF5
> datatypes and how to access them.  And if there is a standard way to make
> compound data types derived from PETSc datatypes.   In short,  how much do
> I need to muck around in HDF5 myself,  and how much can I let PETSc take
> care of?
>
You should be able to use HDF5 exactly as you would use the PETSc binary
viewer and the filesystem. Instead of giving a directory and filename, you
give a groupname


http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Viewer/PetscViewerHDF5PushGroup.html

and the filename is the object name. Then just call View(). We also allow
you to write metadata about the object


http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Viewer/PetscViewerHDF5WriteAttribute.html

     Matt

> -Storm
>
> On Nov 26, 2017 5:49 AM, "Smith, Barry F." <bsmith at mcs.anl.gov> wrote:
>
>>
>>   Storm,
>>
>>    Specifically for TS there is an abstract object called TSTrajectory
>> which is a way to store histories of simulations (it is used by TSAdjoint
>> but also useable for other purposes). It has several ways to store
>> histories and more can be added.
>>
>>    One draw back to saving everything in PETSc binary in one file is that
>> we don't have simple support for random access of a particular vector.
>>
>>    You can also store to HDF5 format and some others that may be useful
>> for you:
>>
>>
>>    Barry
>>
>>
>> > On Nov 26, 2017, at 2:27 AM, Jose E. Roman <jroman at dsic.upv.es> wrote:
>> >
>> >
>> >
>> >> El 26 nov 2017, a las 2:25, Storm Weiner <stormweiner at berkeley.edu>
>> escribió:
>> >>
>> >> Hey there,
>> >>
>> >> For simulations, its useful to store the history as a series of state
>> vectors.  For simulations with many time-steps it can get annoying to store
>> each state vector as a separate file.  It would be useful if there were
>> some way to manage a database of petsc vectors.  To save the current
>> time-step, append the state vector to the database. To restart a
>> simulation, load the corresponding state vector out of the database.
>> >>
>> >> Is there a standard way to do this in PETSc?
>> >>
>> >> Thanks,
>> >> Storm
>> >
>> > In the command line, you can use the “append” option for the viewer.
>> For instance in the MFN solver in SLEPc you can do this:
>> >   $ ./ex23 -mfn_view_solution binary:vectors.bin::append
>> > It will save one vector in each call to MFNSolve(), and all vectors
>> will be stored in the same file ‘vectors.bin’.
>> >
>> > Alternatively, in the source code you can use PetscViewerBinaryOpen()
>> to open the viewer, then save as many vectors as you want with VecView(),
>> and finally close the file with PetscViewerDestroy(). Use VecLoad() to load
>> the vectors.
>> >
>> > Jose
>> >
>>
>>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
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