Polish legacy jet datasets

[comane]

The scope of this PR is to (try to) polish the new implementation of the legacy jet datasets, namely, CMS_2JET_7TEV, CMS_1JET_8TEV, ATLAS_1JET_8TEV_R06, ATLAS_2JET_7TEV_R06.

What the PR does:

1. Adds a filter_utils.utils.py module. This module should collect the functions that are generalisable and could, in principle, be used for all datasets.
2. Adds a filter_utils.legacy_jets_utils.py module that collects all of the utils functions for the filter files. Polishing these is going to be much harder given the nature of the raw data.

[RoyStegeman]

This was not done in this PR, but I changed it since I don't think we should start getting in the habit of suppressing warnings if there is another option

[comane]

This was not done in this PR, but I changed it since I don't think we should start getting in the habit of suppressing warnings if there is another option

Thanks @RoyStegeman, just to be sure I understand: removing the read "r" from with open avoids the pandas warnings?

[RoyStegeman]

No, removing "r" is just because that's the default option anyway.

The warnings are fixed around line 900 in legacy_jets_utils.py.

A similar error, with similar solution, that I didn't fix still exists for ATLAS_2JET_7TEV_R06. I didn't fix it now because that filter.py is broken anyway.

[RoyStegeman]

Since filter files will now share utilities, and we may need to change/fix those shared utilities at some point - do you think it's feasible to run all filters in the CI to test if the output remains unchanged?

[RoyStegeman]

https://github.com/NNPDF/nnpdf/blob/eed00c75b4910606e967d1d0be644a45fd44b913/validphys2/src/validphys/process_options.py#L27

@scarlehoff what should be done in this PR?

[scarlehoff]

@scarlehoff what should be done in this PR?

Change it to pT2 I'd say.

[RoyStegeman]

@comane I see you addressed the CI fails (as pointed out by @Radonirinaunimi), but could you rename p_T2 to pT2?

[comane]

@comane I see you addressed the CI fails (as pointed out by @Radonirinaunimi), but could you rename p_T2 to pT2?

Sure, I am not sure why though? Who wrote that comment there and why is p_T2 wrong? The tests seem to be checking for p_T2 at the moment, not for pT2

So maybe I can simply remove that comment?

[RoyStegeman]

I assume @scarlehoff wrote it. Either way I agree with it for consistency with pT and pT_t

[scarlehoff]

Yes. I think it should be ok.