issues: 1194945072

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id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
1194945072 I_kwDOAMm_X85HOWow 6447 allow merging datasets where a variable might be a coordinate variable only in a subset of datasets 2448579 open 0     1 2022-04-06T17:53:51Z 2022-11-16T03:46:56Z   MEMBER      

Is your feature request related to a problem?

Here are two datasets, in one a is a data_var, in the other a is a coordinate variable. The following fails ``` python import xarray as xr

ds1 = xr.Dataset({"a": ('x', [1, 2, 3])}) ds2 = ds1.set_coords("a") ds2.update(ds1) with 649 ambiguous_coords = coord_names.intersection(noncoord_names) 650 if ambiguous_coords: --> 651 raise MergeError( 652 "unable to determine if these variables should be " 653 f"coordinates or not in the merged result: {ambiguous_coords}" 654 ) 656 attrs = merge_attrs( 657 [var.attrs for var in coerced if isinstance(var, (Dataset, DataArray))], 658 combine_attrs, 659 ) 661 return _MergeResult(variables, coord_names, dims, out_indexes, attrs)

MergeError: unable to determine if these variables should be coordinates or not in the merged result: {'a'} ```

Describe the solution you'd like

I think we should replace this error with a warning and arbitrarily choose to either convert a to a coordinate variable or a data variable.

Describe alternatives you've considered

No response

Additional context

No response

 
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