Writing double and integer attributes into a HDF5 file using Fortran

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1

Hi!

I am using Fortran to create and fill HDF5 files with data. Postprocessing of the created HDF5 files uses h5py, a Python library.

I use the HDF5 Lite API to add a double precision variable as attribute:

call h5ltset_attribute_double_f(outf_id,".",trim(attribute_name(i)),double_variable(i),1,hdferr)

which works fine. But as soon as I read the attribute with h5py I see, that the attribute is added as an array with one single element (array([double_variable])). This complicates postprocessing, hence I am looking for a way to write a single double precision variable as an attribute. Is there a way of doing this with Fortran?

Thanks in advance,

Jürgen

2

Hi Jurgen,

Hi!

I am using Fortran to create and fill HDF5 files with data. Postprocessing of the created HDF5 files uses h5py, a Python library.
I use the HDF5 Lite API to add a double precision variable as attribute:
call h5ltset_attribute_double_f(outf_id,".",trim(attribute_name(i)),double_variable(i),1,hdferr)
which works fine. But as soon as I read the attribute with h5py I see, that the attribute is added as an array with one single element (array([double_variable])).

yes, this was an original design, and, personally, I agree with you that it may not be the best choice for describing the attribute's dataspace. H5S_SCALAR will work better and make more sense in 90% of use cases, but it is too late to change. We should probably be looking into overloading the function and allow some flexibility in the dataspace specification.

This complicates postprocessing, hence I am looking for a way to write a single double precision variable as an attribute. Is there a way of doing this with Fortran?

Yes, you can just use pure HDF5 Fortran API to create a double precision attribute; use
h5screate_f(H5S_SCALAR_F, space_id, hdferr)

call to create a dataspace for the attribute.

Please let me know if you have any questions.

Elena

···

On May 28, 2010, at 8:09 AM, Brommundt Jürgen wrote:

Thanks in advance,
Jürgen
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