H5Part development and discussion

[Jozsef Bakosi <jbakosi AT lanl.gov>]

Thanks, Achim, for the quick response.

I have merged the two steps and now it works using append.

Thanks,
Jozsef
-- 
Jozsef Bakosi
Computational Physics and Algorithms (CCS-2)
MS D413, Los Alamos National Laboratory
Los Alamos, NM 87545, USA
email: jbakosi AT lanl.gov
phone: 505-665-0950
fax: 505-665-4972

On 08.11.2016 23:51, Achim Gsell wrote:
> Hi Jozsef
> 
> > On 11 Aug 2016, at 23:23, Jozsef Bakosi <jbakosi AT lanl.gov> wrote:
> > 
> > Hello,
> > 
> > I have successfully been using H5Part to write particle data to several 
> > time steps.
> > 
> > Now I would like to do the same but without keeping the file open during 
> > time
> > stepping, so I'm attempting to open the file using APPEND, but get the 
> > following
> > error message when I try to call H5PartWriteDataFloat64() with a nonzero 
> > error
> > code:
> > 
> > E: H5PartWriteDataFloat64: Timegroup <= 0.
> > 
> > Here is the sequence that I follow:
> > 
> > I create the file once during initialization:
> > 
> >  f = H5PartOpenFileParallel( filename, H5PART_WRITE, MPI_COMM_WORLD);
> >  H5PartWriteFileAttribString( f, "Origin", "somestring" );
> >  H5PartCloseFile( f );
> > 
> > Then every iteration I repeat:
> > 
> > 1. Write Time stamp:
> > 
> >  f = H5PartOpenFileParallel( filename, H5PART_APPEND, MPI_COMM_WORLD);
> >  H5PartSetStep( f, it );
> >  H5PartSetNumParticles( f, npar );
> >  H5PartCloseFile( f );
> 
> In 1. you create a new step, but that’s it. The H5PartSetNumParticles() 
> call creates a view on the data, but does not create any dataset. The view 
> will be reseted while closing the file.
> 
> > 
> > 2. Write particle coordinates:
> > 
> >  f = H5PartOpenFileParallel( filename, H5PART_APPEND, MPI_COMM_WORLD);
> >  H5PartWriteDataFloat64( f, "x", xdata );
> >  H5PartWriteDataFloat64( f, "y", ydata );
> >  H5PartWriteDataFloat64( f, "z", zdata );
> >  H5PartCloseFile( f );
> 
> This doesn’t work. H5PartOpenFileParallel() does *not* set the time-step to 
> the latest (but empty in your case) step in append mode. Append mode does 
> not mean, you can append new steps only! In append mode you cannot 
> overwrite existing datasets or attributes. But you can add datasets or 
> attributes to existing steps *and* you can add new steps. 
> 
> Best regards
> 
> Achim