`InterferometerData` proposal

@paul-lasky @colm.talbot @moritz.huebner

In the spirit of working next week on cleaning up our open data handling and also detectors.py to see where the bugs live I have a suggestion I'd like to run past you all (I was just thinking about it over coffee and wanted to get it on paper before I forgot - we can discuss it in person next week).

Could we add a InterferomerStrainData class with something like the following attributes:

• frequency_domain_strain
• time_domain_strain
• frequencies
• times
• epoch (may be better named - segment_start_time)
• duration (or segment_duration)
• detector name

And something like the following methods

• set_from_psd
• set_from_frame_file

The basic idea is take what is currently done in Interferometer.set_data and make it a class.

At the same time, it would be good to rename Interferometer.data to Interferometer.strain_data, which would be an instance of the above class. This would (a) make it clear that data is the strain_data and (b) mean that references to the frequencies etc would be Interferometer.strain_data.frequencies which identifies them as the 'frequencies of the strain data' and not, say, of the PSD or anything else. Similarly, it should simplify cases when you have time-series and frequency series as you can just call which ever you want and InterferometerStrainData will have both.

A second reason to do this is that one could imagine (in the future) having InterferometerAuxillaryData also be fed into the likelihood (or just for some other use).

Here are what I think are the basic steps to do this

• Write the class and methods - move logic from set_data to the new class
• Rewrite set_data to just pass the information into InterferometerStrainData
• Turn the 'real data processing' steps into methods of InterferometerStrainData (e.g. download_open_data(), filter_data(), etc
• Rewrite the likelihood to not call interferometer.data, but interferometer.strain_data
• Move plotting tools to a method of this new class and remove duplicated plotting code
• Check through the get_interferometer_with... functions to move logic which belongs in the new class into the new class.

This would then supersede #20 (closed) as it would do that and more.

What do people think? Ideas/suggestions welcome.

I think this is a good idea. It separates some of the logic of the Interferometer and its data in a clear way, because we carry a bunch of things in Interferometer around that don't have that much to do with the Interferometer itself but rather describe the specific set of data.

However, I would argue that the class InterferometerStrainData should contain an attribute Interferometer referring to the Interferometer in which it was recorded and not the other way round. The Interferometer should not be described by any specific set of data, but any sort of InterferometerStrainData should contain information about the Interferometer in which it was recorded. I am not entirely sure, though, if that is the best way to implement it.

Ok I just hacked together a skeleton of what all of this could look like in a new branch: https://git.ligo.org/Monash/tupak/tree/InteferometerStrainData

This is not functioning right now, because I will have to rewrite a bunch of tests and I did not go through every file to adapt these changes.

Right now I left it open if InterferometerStrainData should be an attribute of Interferometer or the other way round (i.e. they are both attributes of each other right now). I think it is quite intuitive which currently implemeted methods and attributes go into the respective classes and most of the code was easy to rearrange because most of everything was already logically quite separated.

mentioned in merge request !72 (merged)

marked the checklist item Write the class and methods - move logic from set_data to the new class as completed

marked the checklist item Rewrite set_data to just pass the information into InterferometerStrainData as completed

marked the checklist item Rewrite the likelihood to not call interferometer.data, but interferometer.strain_data as completed

marked the checklist item Move plotting tools to a method of this new class and remove duplicated plotting code as completed

marked the checklist item Check through the get_interferometer_with... functions to move logic which belongs in the new class into the new class. as completed

added Feature-request ~672 labels

changed the description

closed

unassigned @gregory.ashton