[petsc-users] petsc4py, plotting DA and writing to file

[Lisandro Dalcin]

On 27 September 2010 14:02, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
> On Sep 27, 2010, at 11:47 AM, Lisandro Dalcin wrote:
>
>> On 27 September 2010 13:33, Barry Smith <bsmith at mcs.anl.gov> wrote:
>>>
>>>  Lisandro
>>>
>>>    In C he could do VecView(vec,PETSC_VIEWER_DRAW_WORLD); can he not do the equivalent in Python?
>>> What syntax would he use?
>>
>> viewer = PETSc.Viewer.DRAW(globalvec.comm)
>> globalvec.view(viewer) # or viewer(globalvec)
>>
>>>
>>> Perhaps the 2d bratu python example could demonstrate this since it is simple and there is no monkeying with copying to one process etc.
>>>
>>
>> Well, that example does not even use a DA, the plot is going to be a bit ugly.
>
>  Sorry. Barry
>

I could add a poisson2d implemented with DA and working in parallel.


>>
>>>   Barry
>>>
>>> On Sep 27, 2010, at 11:27 AM, Lisandro Dalcin wrote:
>>>
>>>> On 27 September 2010 13:12, Amal Alghamdi <amal.ghamdi at kaust.edu.sa> wrote:
>>>>> Dear All,
>>>>> I'm using the DA structure in petsc4py. I'd like to know please what is the
>>>>> right way to:
>>>>> plot the DA vector (the global vector).
>>>>> write the global vector to a file.
>>>>> Is that each process writes or draws its own part? or I should communicate
>>>>> all the data to one process? or none of these?!!
>>>>> Thank you very much
>>>>> Amal
>>>>
>>>> Use a PETSc.Viewer().createBinary() to save the global vector. Each
>>>> process will save its own part.
>>>>
>>>> In order to plot it, I think you should use numpy.fromfile() to load
>>>> the data, and then plot the array.
>>>>
>>>> Other way would be to use a PETSc.Scatter.toZero() to get the data at
>>>> process 0, and then plot it
>>>>
>>>> scatter, seqvec = PETSc.Scatter.toZero(globalvec)
>>>> im = PETSc.InsertMode.INSERT_VALUES
>>>> sm = PETSc.ScatterMode.FORWARD
>>>> scatter.scatter(globalvec, seqvec, im, sm)
>>>> if globalvec.comm.rank == 0:
>>>>    plot(seqvec.array)
>>>>
>>>>
>>>> --
>>>> Lisandro Dalcin
>>>> ---------------
>>>> CIMEC (INTEC/CONICET-UNL)
>>>> Predio CONICET-Santa Fe
>>>> Colectora RN 168 Km 472, Paraje El Pozo
>>>> Tel: +54-342-4511594 (ext 1011)
>>>> Tel/Fax: +54-342-4511169
>>>
>>>
>>
>>
>>
>> --
>> Lisandro Dalcin
>> ---------------
>> CIMEC (INTEC/CONICET-UNL)
>> Predio CONICET-Santa Fe
>> Colectora RN 168 Km 472, Paraje El Pozo
>> Tel: +54-342-4511594 (ext 1011)
>> Tel/Fax: +54-342-4511169
>
>



-- 
Lisandro Dalcin
---------------
CIMEC (INTEC/CONICET-UNL)
Predio CONICET-Santa Fe
Colectora RN 168 Km 472, Paraje El Pozo
Tel: +54-342-4511594 (ext 1011)
Tel/Fax: +54-342-4511169