[Nexus] Correct way to specify multiple signals

[Jacob.Filik at Diamond.ac.uk]

Another suggestion might just be to put any extra auxiliary NXdata inside the raw NXdata.

I fear this conversion is going into dangerous/interesting territory. Software packages usually have an associated file format, which is strongly linked to the application and its data model.

Is it the job of Nexus to allow NeXpy/DAWN/Mantis/Mantid… to be able open a processed file from pyMCA of raw data, say collected at Diamond, and display it in a the “richest” way it can? Where richest is a function of how deeply the application developer has implemented reading the standard?

I can understand that it may not be the job of Nexus to provide a complete application data model for all experiments and all applications ever, but wanting an application to be able to plot 2 related datasets at the same time seems like it shouldn’t be out the scope (but also should not break applications using a more simple Nexus structure).

Anyway, just my point of view.

Jake


From: NeXus [mailto:nexus-bounces at shadow.nd.rl.ac.uk] On Behalf Of V. Armando Solé
Sent: 11 January 2018 14:40
To: nexus at nexusformat.org
Subject: Re: [Nexus] Correct way to specify multiple signals

On 11/01/2018 15:36, Osborn, Raymond wrote:
I saw the Github issue and responded before I realized there was already a lengthy correspondence here. I will have to read more carefully what has already been contributed here, but I wanted to quickly summarize what I wrote there (https://github.com/nexusformat/NIAC/issues/25):

“In my view, it is the role of the NeXus standard to provide a way to offer a default plot for each NXdata group, but I don't think it is necessary for NeXus to then specify all other possible non-default plots. Any program is free to provide that option within the current standard as NeXpy does.”

Please see the issue for my reasoning - basically, you can do what Armando requests, i.e., plot multiple signals, now without adding extra complexity to the standard.

The goal is not to foresee any possible plot. It is to provide a default plot. I post the answer I sent to github here too:

On 11/01/2018 15:04, Ray Osborn wrote:

To summarize - in my view, it is the role of the NeXus standard to

provide a way to offer a default plot for each NXdata group,

Exact, but to me the default plot for a fit is the raw_data, the used

uncertainties and the fitted curve.



NeXus provides everything for it except the possibility to put the

auxiliary curve.





but I don't think it is necessary for NeXus to then specify all other

possible non-default plots.

Nobody is asking for it.



Any program is free to provide that option within the current standard

as NeXpy does.

PyMca does it too, so that is not the problem. However, consider the

marvellous opportunity NeXus offers to provide the output of a fit (or

other treatments), with uncertainties, axis labels, and fitted curve at

the cost of defining two group attributes.



If NIAC tells me that Peter Chang's solution is not going to be

considered at all, it is fine with me too. We'll implement those two

attributes at our side and they will not conflict with any other

implementation.



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