nexusformat / exampledata Goto Github PK

• refers to file tree (#10)
• critique is now simpler than described (#14)

some of the data files here are not compliant with the NeXus standard

there could be several categories:

• compliant HDF4 files (deprecated for new use)
• compliant XML files (deprecated for new use)
• compliant HDF5 files
• non-compliant data files
• non-compliant data files to be kept for testing

related to nexusformat/definitions#280

extend nxdl_to_hdf5.py to generate h5py and nexusformat scripts that will create hdf5 files of all application definitions

to let users know that there are examples of all application def's in the form of:

• hdf5 files
• python scripts to create the structure of the definition using h5py
• python scripts to create the structure of the definition using nexusformat

It is difficult to find an example of a specific application definition, which is what most people coming to this repository will want to do.

Dear Nexus community,
Could I ask here for advice, please?

NXdetector has an entry called type
https://manual.nexusformat.org/classes/base_classes/NXdetector.html

"Description of type such as He3 gas cylinder, He3 PSD, scintillator, fission chamber, proportion counter, ion chamber, ccd, pixel, image plate, CMOS, …"

How do I implement this with h5py correctly?
The manual for h5py does not give an example for string datasets. https://docs.h5py.org/en/stable/strings.html#storing-strings

My approach:

uv_spectra=grp_uv.create_group("uv_spectra")
uv_spectra.attrs["NX_class"] = 'NXdetector'
string_dt = h5py.special_dtype(vlen=str)
uv_spectra_type=uv_spectra.create_dataset('type', data='ccd', dtype=string_dt)

But I don't know if this is the correct way.
Thank you for your help.

as per the NIAC call on Nov 15 2021 there was a desire that there would be hdf5 representations of proposed definitions, nxdl_to_hdf5.py will be extended to generate hdf5 files and scripts for the definitions that exist in the contributed_definitions folder.

There are a variety of files in this repository. Only some of them are valid NeXus files, including HDF4, XML, and HDF5 files.

Provide some assistance to identify the examples of compliant NeXus files.

Large files can become a problem in a repository in many ways. Consider use of large file storage:

• https://github.blog/2015-10-14-managing-large-files-with-git-lfs/
• https://dzone.com/articles/git-lfs-why-and-how-to-use
• https://about.gitlab.com/blog/2017/01/30/getting-started-with-git-lfs-tutorial/