[NeXus-committee] Fwd: Examples of irregular grids

[Osborn, Raymond]

Hi everyone,
I’m not sure how much work I will be able to do in parallel to the code camp (which I can’t attend), but I would like to include some discussion next week of the issue I raised a few weeks ago about the ‘_indices’ method of defining axes. I am concerned that I still don’t have a working example of a file that uses  this part of the standard, apart from the canSAS example, which appears to be broken. One of the things that I can do in NeXpy is test the extent to which any standard is parsable, since I aim to cover every possible variant of the standard that has existed. The latest version, for example, handles different ways of defining a field’s uncertainties, i.e., both adding an attribute called ‘uncertainties’ to the field or another field with the same name + ‘_errors’. The ‘_indices’ attributes could be difficult because they could have different dimensionalities, as I understand it, i.e, 1D if they are simple axes or multi-D if they are pixel coordinates or vertices, but I can’t check that until I have some real-world examples. This might provide useful feedback into how they should be used.

If you have any examples of NeXus files with irregular grids using the ‘_indices’ attributes, I would really appreciate seeing them, if they could be put on an FTP server or Dropbox.

Thanks,
Ray

Begin forwarded message:

From: "Osborn, Raymond" <rosborn at anl.gov<mailto:rosborn at anl.gov>>
Subject: [NeXus-committee] Examples of irregular grids
Date: September 15, 2017 at 9:02:19 AM CDT
To: NeXus Committee <nexus-committee at nexusformat.org<mailto:nexus-committee at nexusformat.org>>

Hi everyone,
In preparation for the code camp, I’m having a look to see how it might be possible to add support in the Python API for the ‘_indices’ method of defining axes, but I need some examples because I’m not sure I fully understand the documentation. Do people have examples of HDF5 files with irregular grids defined according to the latest NeXus standard, and could they make them available somehow? If they are too large, could they be put on an FTP server?

Also, if you have functions that plot such data, would you be able to supply the parsing and plotting code? I prefer Python, but I can probably decipher C++ or Java if that is what you have. I need to see how this would map onto Matplotlib’s pcolormesh function.

Thanks,
Ray
--
Ray Osborn, Senior Scientist
Materials Science Division
Argonne National Laboratory
Argonne, IL 60439, USA
Phone: +1 (630) 252-9011
Email: ROsborn at anl.gov<mailto:ROsborn at anl.gov>

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--
Ray Osborn, Senior Scientist
Materials Science Division
Argonne National Laboratory
Argonne, IL 60439, USA
Phone: +1 (630) 252-9011
Email: ROsborn at anl.gov<mailto:ROsborn at anl.gov>

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