[Nexus-developers] NeXus Quo Vadis

[Ray Osborn]

I want to support the idea that there is tremendous value to encouraging the use of NeXus in this way  - in fact, it is the way I have been using NeXus for years - as a way of loosely connecting data that are not necessarily defined by a strict standard. As Pete suggested, I would add that every NeXus file should contain at least one NXdata group, and I think people should be encouraged to use the glossary rather than inventing all their own terms, if they exist. 

This, of course, requires access to flexible tools (usually scripting tools) that allow you to handle whatever data you are given interactively. If you are writing formal data analysis applications, you will have to be much stricter in requiring the input data to conform to some standard, but if you are using a scripting toolbox to play with the data, that is unnecessary. Hence my interest in the Python tree API (which I hope will be included in the 4.3 release).

Ray

On Feb 20, 2012, at 11:07 AM, Pete R. Jemian wrote:

> I like this.
> 
> On 2/20/2012 10:54 AM, "V. Armando Solé" wrote:
>> """
>> 2. Store your data in a simplified hierarchy using NXentry and
>> NXcollection groups. Apply a lot of
>> freedom how you do this.
>> """
>> 
>> NXentry mandatory.
>> NXcollection for anything not dealt with by other NXclass.
>> 
>> If you want to describe your beamline, then there is a group
>> (NXinstrument) for that. I would not write it into an NXcollection.
>> Personally I like how ALBA is generating Nexus files.
> 
> This is actually a good model for the EPICS areaDetector, NeXus file plugin, to use.  So, the basic structure I have been recommending is:
> 
> <file>
>   NXentry (required)
>     NXdata (required)
>       data : contains the image
>     NXcollection (optional)
>       user-supplied list of uncategorized metadata
>     NXinstrument (optional)
>       metadata organized as defined in the NeXus dictionary
> 
> links may be used to avoid replicating information, if that is important
> 
> -- 
> ----------------------------------------------------------
> Pete R. Jemian, Ph.D.                <jemian at anl.gov>
> Beam line Controls and Data Acquisition, Group Leader
> Advanced Photon Source,   Argonne National Laboratory
> Argonne, IL  60439                   630 - 252 - 3189
> -----------------------------------------------------------
>    Education is the one thing for which people
>       are willing to pay yet not receive.
> -----------------------------------------------------------
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-- 
Ray Osborn
Materials Science Division
Argonne National Laboratory
Argonne, IL 60439, USA
Phone: +1 (630) 252-9011
Email: ROsborn at anl.gov