issue_comments: 1268380486

Hi everyone, first of all, thanks for your amazing work! I came across this issue today because I have a dataset with multiple variables and multiple multi index dimensions, some of which aren't used in some variable. I had to slightly adapt the workaround posted by @dcherian to get things to work. I'll post it here if someone else finds the patch useful. I'm not sure if it would be a viable fix for the issue though, let me know if it is and I'll open a PR.

```python def encode_multiindex(ds, idxname): encoded = ds.reset_index(idxname) coords = dict(zip(ds.indexes[idxname].names, ds.indexes[idxname].levels)) for coord in coords: encoded[coord] = coords[coord].values shape = [encoded.sizes[coord] for coord in coords] encoded[idxname] = np.ravel_multi_index(ds.indexes[idxname].codes, shape) encoded[idxname].attrs["compress"] = " ".join(ds.indexes[idxname].names) return encoded

def decode_to_multiindex(encoded, idxname): names = encoded[idxname].attrs["compress"].split(" ") shape = [encoded.sizes[dim] for dim in names] indices = np.unravel_index(encoded[idxname].values, shape) arrays = np.array([encoded[dim].values[index] for dim, index in zip(names, indices)]) mindex = pd.MultiIndex.from_arrays(arrays, names=names)

decoded = xr.Dataset(
    {},
    dict(
        **{idxname: mindex},
        **{dim: encoded.coords[dim] for dim in encoded.dims if dim not in [idxname] + names}
    )
)
for varname in encoded.data_vars:
    if idxname in encoded[varname].dims:
        decoded[varname] = (encoded[varname].dims, encoded[varname].values)
    else:
        decoded[varname] = encoded[varname]
return decoded

```