Explicit check for matching coords

This has been an issue on my mind for awhile. But we need to have something in checks.py that acts as a decorator to check that the input Datasets/DataArrays being compared have the same coordinate labeling (outside of time).

For instance,

import climpred
hind = climpred.tutorial.load_dataset('CESM-DP-SST-3D')
verif = climpred.tutorial.load_dataset('FOSI-SST-3D')

# Add nlat/nlon coordinates only on one.
h['nlat'] = np.arange(h.nlat.size)
h['nlon'] = np.arange(h.nlon.size)

climpred.prediction.compute_hindcast(h, v, max_dof=True)

This returns

ValueError: indexes along dimension 'nlat' are not equal

I’ve encountered this a lot when something I’m comparing to drops coords along the way or doesn’t have them to begin with. And it makes you think something in climpred is broken during alignment, like we’re losing spatial cells. In reality it’s just that one has a coordinate for nlat and one doesn’t.

[bradyrx]

That’s a good point regarding people wanting to regrid. Maybe just throw a warning. Whenever you add a dataset, check the union of coords and warn if they don’t match.

[aaronspring]

Or we don’t do this coords checking (only do it for time to check calendar) because then we could use xesmf regridding to regrid different datasets to 1x1 or 5x5 der grids which then should match