Best practice for retrieving Dependent Variables from an ObservationCollection

[luigigisolfi]

Hi everyone,

I am working on simulating observations and have successfully attached dependent variables (specifically Azimuth and Elevation) to my simulation settings. My setup looks essentially like this:

# this is a function
def create_obs_collection(args):
  [...]
  [...]
  # Define Dependent Variable Settings
  az_settings = observations_setup.observations_dependent_variables.azimuth_angle_dependent_variable(links.receiver)
  el_settings = observations_setup.observations_dependent_variables.elevation_angle_dependent_variable(links.receiver)
  
  # Add them to the Simulation Settings
  observations_setup.observations_dependent_variables.add_dependent_variables_to_observable(
      rso_sim_settings,
      [az_settings, el_settings],
      body_system,
      observable_type
  )
 
   [...]
   [...]
  observations.compute_residuals_and_dependent_variables(
      rso_observations, observation_simulators, bodies)

return rso_observations

After simulating the observations and getting the resulting ObservationCollection, I want to extract the actual values of these dependent variables in my script.

Currently, I am passing the setting objects back into the dependent_variable method of the collection. If I am in a different scope (or script) than where they were defined, I have to re-instantiate identical setting objects to use as keys (see also user guide https://docs.tudat.space/en/latest/user-guide/state-estimation/observation-simulation/observation-collection-manipulation/dependent-variables.html):

# this is a callable script 
rso_observations = create_obs_collection(args)
# Re-create the settings objects to use as keys for retrieval
az_settings_retrieval = observations_setup.observations_dependent_variables.azimuth_angle_dependent_variable(links.receiver)
el_settings_retrieval = observations_setup.observations_dependent_variables.elevation_angle_dependent_variable(links.receiver)

# Retrieve the values
az_values = rso_observations.dependent_variable(az_settings_retrieval)[0]
el_values = rso_observations.dependent_variable(el_settings_retrieval)[0]

My doubt is: it feels slightly redundant to re-create the settings object just to query the collection.
Is there a way to retrieve a list of available dependent variables directly from the ObservationCollection, or access these values using a simpler identifier rather than the full settings object?