Enabling single ifo runs in PyGRB workflows

[sebastiangomezlopez]

Standard information about the request

This is a: bug fix

This change affects: PyGRB

This change changes: scientific output

Disclaimer: This PR has not been fully tested yet. DO NOT merge

The proposed changes in this Pull request include:

• An expansion of the single IFO case at the pycbc_make_sky_grid level.
• minor fixes to pycbc_multi_inspiral that were preventing the creation of "trivial" time_delay dictionaries when slide_num=0, and slide_id related lists and dictionaries only contain the 0 element.

Motivation

Contents

Links to any issues or associated PRs

Testing performed

Additional notes

• The author of this pull request confirms they will adhere to the code of conduct

[pannarale]

I would keep the changes to the 2 files in 2 distinct PRs. The changes to pycbc_make_skygrid are solid and this PR could be renamed appropriately. Changes to pycbc_multi_inspiral require more thought, in my opinion.

[titodalcanton]

The changes to make_sky_grid relate to some design considerations I made in #4995.

I am not a big fan of structuring code like this:

if some_condition:
    # do something short and simple
else:
    # do something very long and complicated

I would prefer something like this instead:

def make_single_det_grid(args):
    # do something short and simple

def make_multi_det_grid(args):
    # do something very long and complicated

if one_det_given:
    make_single_det_grid(args)
else:
    make_multi_det_grid()

There is also the consideration that @Thomas-JACQUOT is working on a deep rewrite of make_skymap anyway to support the HEALPix input… Maybe we should spend some time at the next call to find a good design for the various use cases.