Combine spatial data and xarray point obs

[zmoon]

xref: NOAA-CSL/MELODIES-MONET#115

• new combine_da_to_da utility function
  • currently used in MM aircraft branch here
• .monet combine_da methods
  • maybe later create a new combine method that could take xarray or df point data input
• improve docstrings of some combine functions and .monet accessor methods

[zmoon]

@bbakernoaa when you get a chance could you let me know what remains to be done here?

[bbakernoaa]

I don't think anything else needs to be done here. We have been using this in the MELODIES-MONET project so I think it should be ready to merge.

[zmoon]

@bbakernoaa in the new functions the docstring parameters listed don't match the signature in some cases, and for some I am not sure how to fix. Would you be able to have a quick go at that?

[bbakernoaa]

I'll try to take a look at it soon

[zmoon]

@bbakernoaa I made some edits. I am a little confused though: for combine_da it seems like the data argument should be a DataFrame, as it is being passed to combine_da_to_df in the df position, but the checks in combine_da make sure that it is an xarray Dataset. The combine_da signature seems to suggest the intention was for the new combine_da_to_da to be used instead?

[bbakernoaa]

@zmoon lets talk about this tomorrow as I'm a little confused

[zmoon]

@rschwant could you point to me how/where in MM you are using this?