Add to_collection method returning an Xcollection

[jukent]

Change Summary

Updating to_dataset_dict to return an xcollection.Collection object.

Needed to add git+git://github.com/NCAR/xcollection.git to requirements
And wrap dictionaries in xc.Collection

There are some uses of the word "Collection" throughout the file that are not an xc.Collection, we might want to be very specific with our language throughout.

Tests seem to be unchanged by Collection vs Dictionary typing, maybe add an assert type test.

Related issue number

• Fixes Use Collection object implementation from NCAR/xcollection in intake-esm #382

Checklist

• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable

[jukent]

In the tests we have

)
def test_to_dataset_dict(path, query, xarray_open_kwargs):
    cat = intake.open_esm_datastore(path)
    cat_sub = cat.search(**query)
    _, ds = cat_sub.to_dataset_dict(xarray_open_kwargs=xarray_open_kwargs).popitem()
    assert 'member_id' in ds.dims
    assert len(ds.__dask_keys__()) > 0
    assert ds.time.encoding

But an xc.Collection won't have dims

[jukent]

@kmpaul This is failing with "Error: The process '/usr/share/miniconda3/condabin/mamba' failed with exit code 1" which seems to be the same as from the ProjectPythia pull requests (related to the new mamba version?). I'm looking for how you fixed that in those repositories now.

ProjectPythia/projectpythia.github.io@8d5411e

[kmpaul]

Error in protocol

[andersy005]

Thank you for working on this, @jukent! Looks great!

[kmpaul]

Thanks, @jukent!