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/issues/5384#issuecomment-849935768,https://api.github.com/repos/pydata/xarray/issues/5384,849935768,MDEyOklzc3VlQ29tbWVudDg0OTkzNTc2OA==,404832,2021-05-27T20:56:04Z,2021-05-27T20:56:04Z,CONTRIBUTOR,"Interesting! Thanks for the heads-up, @benbovy. I'll keep my eye on that.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,903055859
https://github.com/pydata/xarray/issues/5384#issuecomment-849733928,https://api.github.com/repos/pydata/xarray/issues/5384,849733928,MDEyOklzc3VlQ29tbWVudDg0OTczMzkyOA==,4160723,2021-05-27T15:35:18Z,2021-05-27T15:35:18Z,MEMBER,"This should be fixed in #5385.

Side note: the example you gave here, i.e.,

```python
ds = Dataset({'d': DataArray(c.data, dims=['c'])}, coords=c.coords)
ds = ds.unstack(['c'])
```

should probably be depreciated after the index refactoring in Xarray (currently WIP), which aims to decouple the concepts of coordinates vs. indexes. More specifically, indexes shouldn't be passed implicitly via the `coords` argument of the `Dataset`/`DataArray` constructors anymore, but instead explicitly via the `indexes` argument (see https://github.com/pydata/xarray/blob/master/design_notes/flexible_indexes_notes.md#22-explicit-vs-implicit-index-creation).","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,903055859
https://github.com/pydata/xarray/issues/5384#issuecomment-849602816,https://api.github.com/repos/pydata/xarray/issues/5384,849602816,MDEyOklzc3VlQ29tbWVudDg0OTYwMjgxNg==,4160723,2021-05-27T12:44:08Z,2021-05-27T12:44:08Z,MEMBER,This has been introduced in #5102. I'm looking into it.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,903055859
https://github.com/pydata/xarray/issues/5384#issuecomment-849271660,https://api.github.com/repos/pydata/xarray/issues/5384,849271660,MDEyOklzc3VlQ29tbWVudDg0OTI3MTY2MA==,404832,2021-05-27T02:35:51Z,2021-05-27T02:35:51Z,CONTRIBUTOR,"> I'm not sure how common it is for MultiIndexes to have a single index, but we should be general over any number.

That makes sense, and it actually pretty much sums up how I encountered this. My code here is a reduction of a function I wrote that was supposed to work with a fairly general array and subset of its dimensions, and I happened to call it with a one-element dimension list.

> We'd definitely take a fix for this.

In principle, I'd be happy to help, but I haven't gone into the `xarray` internals at all yet, nor do I have the dev environment set up (in particular, I don't have `conda`), so it would probably take me a while.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,903055859
https://github.com/pydata/xarray/issues/5384#issuecomment-849246165,https://api.github.com/repos/pydata/xarray/issues/5384,849246165,MDEyOklzc3VlQ29tbWVudDg0OTI0NjE2NQ==,5635139,2021-05-27T01:31:49Z,2021-05-27T01:32:18Z,MEMBER,"This does look like a bug, specifically affecting MultiIndexes containing only one Index.

The issue seems to be that `self.get_index('c')` returns a normal index:

```python
   4020             non_multi_dims = [
   4021                 d for d in dims if not isinstance(self.get_index(d), pd.MultiIndex)
   4022             ]
   4023             if non_multi_dims:
-> 4024                 raise ValueError(
   4025                     ""cannot unstack dimensions that do not ""
   4026                     f""have a MultiIndex: {non_multi_dims}""
   4027                 )
   4028
   4029         result = self.copy(deep=False)
   4030         for dim in dims:

ipdb> self.get_index('c')
Index([(0,)], dtype='object')   # <- single index

ipdb> self
<xarray.Dataset>
Dimensions:  (c: 1)
Coordinates:
  * c        (c) MultiIndex   # <- multi index
  - b        (c) int64 0
    a        (c) int64 0
Data variables:
    d        (c) int64 0
```

I'm not sure how common it is for MultiIndexes to have a single index, but we should be general over any number. 

We'd definitely take a fix for this. ","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,903055859