html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/pull/7150#issuecomment-1276290679,https://api.github.com/repos/pydata/xarray/issues/7150,1276290679,IC_kwDOAMm_X85MEqZ3,21131639,2022-10-12T14:38:22Z,2022-10-12T14:38:22Z,CONTRIBUTOR,"> Could you also update whats_new.rst with your contribution please?
Done 👍 ","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1403144601
https://github.com/pydata/xarray/pull/7150#issuecomment-1274605144,https://api.github.com/repos/pydata/xarray/issues/7150,1274605144,IC_kwDOAMm_X85L-O5Y,21131639,2022-10-11T12:25:57Z,2022-10-11T12:25:57Z,CONTRIBUTOR,"> Would it be possible to add a test with a multi-index?
I added such a test now (which fails with the old version of `_protect_dataset_variables_inplace` but runs through with the updated version of this PR)","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1403144601
https://github.com/pydata/xarray/issues/7139#issuecomment-1273284963,https://api.github.com/repos/pydata/xarray/issues/7139,1273284963,IC_kwDOAMm_X85L5Mlj,21131639,2022-10-10T13:04:30Z,2022-10-10T13:04:30Z,CONTRIBUTOR,"Based on your suggestion above I tried this single line fix which resolved my issue: https://github.com/pydata/xarray/pull/7150
However I'm not sure if this is the correct approach, since I'm not all to deeply familiar with the indexing model.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1400949778
https://github.com/pydata/xarray/issues/7139#issuecomment-1272922855,https://api.github.com/repos/pydata/xarray/issues/7139,1272922855,IC_kwDOAMm_X85L30Ln,21131639,2022-10-10T07:59:01Z,2022-10-10T07:59:01Z,CONTRIBUTOR,"Here is the full stacktrace:
```python
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
Cell In [12], line 7
----> 7 loaded = xr.open_dataset(""multiindex.nc"", engine=""netcdf4-multiindex"", handle_multiindex=True)
8 print(loaded)
File ~/.local/share/virtualenvs/test-oePfdNug/lib/python3.8/site-packages/xarray/backends/api.py:537, in open_dataset(filename_or_obj, engine, chunks, cache, decode_cf, mask_and_scale, decode_times, decode_timedelta, use_cftime, concat_characters, decode_coords, drop_variables, inline_array, backend_kwargs, **kwargs)
530 overwrite_encoded_chunks = kwargs.pop(""overwrite_encoded_chunks"", None)
531 backend_ds = backend.open_dataset(
532 filename_or_obj,
533 drop_variables=drop_variables,
534 **decoders,
535 **kwargs,
536 )
--> 537 ds = _dataset_from_backend_dataset(
538 backend_ds,
539 filename_or_obj,
540 engine,
541 chunks,
542 cache,
543 overwrite_encoded_chunks,
544 inline_array,
545 drop_variables=drop_variables,
546 **decoders,
547 **kwargs,
548 )
549 return ds
File ~/.local/share/virtualenvs/test-oePfdNug/lib/python3.8/site-packages/xarray/backends/api.py:345, in _dataset_from_backend_dataset(backend_ds, filename_or_obj, engine, chunks, cache, overwrite_encoded_chunks, inline_array, **extra_tokens)
340 if not isinstance(chunks, (int, dict)) and chunks not in {None, ""auto""}:
341 raise ValueError(
342 f""chunks must be an int, dict, 'auto', or None. Instead found {chunks}.""
343 )
--> 345 _protect_dataset_variables_inplace(backend_ds, cache)
346 if chunks is None:
347 ds = backend_ds
File ~/.local/share/virtualenvs/test-oePfdNug/lib/python3.8/site-packages/xarray/backends/api.py:239, in _protect_dataset_variables_inplace(dataset, cache)
237 if cache:
238 data = indexing.MemoryCachedArray(data)
--> 239 variable.data = data
File ~/.local/share/virtualenvs/test-oePfdNug/lib/python3.8/site-packages/xarray/core/variable.py:2795, in IndexVariable.data(self, data)
2793 @Variable.data.setter # type: ignore[attr-defined]
2794 def data(self, data):
-> 2795 raise ValueError(
2796 f""Cannot assign to the .data attribute of dimension coordinate a.k.a IndexVariable {self.name!r}. ""
2797 f""Please use DataArray.assign_coords, Dataset.assign_coords or Dataset.assign as appropriate.""
2798 )
ValueError: Cannot assign to the .data attribute of dimension coordinate a.k.a IndexVariable 'measurement'. Please use DataArray.assign_coords, Dataset.assign_coords or Dataset.assign as appropriate.
```","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1400949778
https://github.com/pydata/xarray/issues/6752#issuecomment-1236917784,https://api.github.com/repos/pydata/xarray/issues/6752,1236917784,IC_kwDOAMm_X85Jud4Y,21131639,2022-09-05T12:07:13Z,2022-09-05T12:07:13Z,CONTRIBUTOR,"Thanks for the suggestions, I'll look into this `Indexes.group_by_index` and see if that is able to resolve our issue.
And with regards to the (de)serialization: I haven't investigated yet how the `index` changes in `2022.6` affect our initial usecase, maybe an approach such as the suggested with a custom backend may be even a better solution for us then.
Though probably we would ideally need a way to override [NetCDF4BackendEntrypoint](https://github.com/pydata/xarray/blob/main/xarray/backends/netCDF4_.py#L518) with another Entrypoint as the default for `.nc` files
As for the original issue discussed here: That can probably be closed then, since it was an intentional change.
But finding information about those changes right now was not so easy, is there some resource available where I can read up about the changes to `indexes` and functions related to them. (e.g. I was unaware of the existence of `xindexes` or `Indexes.group_by_index`)?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1293460108
https://github.com/pydata/xarray/issues/6752#issuecomment-1236717180,https://api.github.com/repos/pydata/xarray/issues/6752,1236717180,IC_kwDOAMm_X85Jts58,21131639,2022-09-05T08:51:24Z,2022-09-05T08:51:24Z,CONTRIBUTOR,"@benbovy I also just tested the `get_unique()` method that you mentioned and maybe noticed a related issue here, which I'm not sure is wanted / expected.
Taking the above dataset `ds`, accessing this function results in an error:
```python
> ds.indexes.get_unique()
TypeError: unhashable type: 'MultiIndex'
```
However, for `xindexes` it works:
```python
> ds.xindexes.get_unique()
[<xarray.core.indexes.PandasMultiIndex at 0x7f105bf1df20>]
```","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1293460108
https://github.com/pydata/xarray/issues/6752#issuecomment-1236714136,https://api.github.com/repos/pydata/xarray/issues/6752,1236714136,IC_kwDOAMm_X85JtsKY,21131639,2022-09-05T08:48:23Z,2022-09-05T08:48:23Z,CONTRIBUTOR,"We used the `.indexes` property to implement a workaround for serializing Datasets containing multiindices to `netCDF`. For this the implementation basically looked like this:
(Inspired by and related to this issue: https://github.com/pydata/xarray/issues/1077)
Saving dataset as NetCDF:
1. Loop over `dataset.indexes`
2. Check if index is a multi index
3. If so, encode it somehow and save it as attribute in the dataset
4. Reset (remove) the index
5. Now save this ""patched"" dataset as NetCDF
And then loading it again:
1. Load the dataset
2. Check if this special attribute exists
3. If so decode the multiindex and set it as index in the dataset
When testing the pre-release version I noticed some of our tests failing, which is why I raised this issue in the first place - in case those changes were unwanted. I was not aware that you were actively working on multi index changes and therefore expecting API changes here. With that in mind I'll probably be able to adapt our code to this new API of `indexes` and `xindexes`.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1293460108