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/1847#issuecomment-391498368,https://api.github.com/repos/pydata/xarray/issues/1847,391498368,MDEyOklzc3VlQ29tbWVudDM5MTQ5ODM2OA==,782050,2018-05-23T21:13:41Z,2018-05-23T21:13:41Z,NONE,"I think that the behavior is consistent with expected upcasting, (so no bug on your side), but we haven't figured out where we are using unicode vs string.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,290320242
https://github.com/pydata/xarray/pull/1847#issuecomment-391497264,https://api.github.com/repos/pydata/xarray/issues/1847,391497264,MDEyOklzc3VlQ29tbWVudDM5MTQ5NzI2NA==,1217238,2018-05-23T21:09:43Z,2018-05-23T21:09:43Z,MEMBER,"@smithsp OK, I'd be happy to take a look if you're able to track it down into a self-contained example.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,290320242
https://github.com/pydata/xarray/pull/1847#issuecomment-391224085,https://api.github.com/repos/pydata/xarray/issues/1847,391224085,MDEyOklzc3VlQ29tbWVudDM5MTIyNDA4NQ==,782050,2018-05-23T05:23:15Z,2018-05-23T05:23:15Z,NONE,"@shoyer Thank you for inquiring after the link.  The link is to a private repository (although we have never denied someone who requests access.) It may become public some day.  We encountered a problem when switching to version 10 or 11 of xarray, because of this fix, as we seemed to be combining strings and unicode in a `concat` operation.  We have since fixed our specific bug, although we have not tracked down the exact combination of variables that led to upcasting to the object dtype.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,290320242
https://github.com/pydata/xarray/pull/1847#issuecomment-391196199,https://api.github.com/repos/pydata/xarray/issues/1847,391196199,MDEyOklzc3VlQ29tbWVudDM5MTE5NjE5OQ==,1217238,2018-05-23T02:00:56Z,2018-05-23T02:00:56Z,MEMBER,@smithsp that link doesn't work. Did you mean to refer to something else?,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,290320242
https://github.com/pydata/xarray/pull/1847#issuecomment-390728302,https://api.github.com/repos/pydata/xarray/issues/1847,390728302,MDEyOklzc3VlQ29tbWVudDM5MDcyODMwMg==,782050,2018-05-21T17:42:23Z,2018-05-21T17:42:23Z,NONE,Mention https://github.com/gafusion/OMFIT-source/pull/2734.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,290320242
https://github.com/pydata/xarray/pull/1847#issuecomment-364793621,https://api.github.com/repos/pydata/xarray/issues/1847,364793621,MDEyOklzc3VlQ29tbWVudDM2NDc5MzYyMQ==,1217238,2018-02-11T22:04:29Z,2018-02-11T22:04:29Z,MEMBER,"I added fixes (bool, float) -> object and (str, bytes) -> object, and also applied these to `concatenate`/`stack` as well as `where` in `duck_array_ops`.

From a user-facing perspective, this now fixes dtypes `xarray.concat()` for mixed dtypes as well.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,290320242
https://github.com/pydata/xarray/pull/1847#issuecomment-364353009,https://api.github.com/repos/pydata/xarray/issues/1847,364353009,MDEyOklzc3VlQ29tbWVudDM2NDM1MzAwOQ==,1217238,2018-02-09T07:05:01Z,2018-02-09T07:05:01Z,MEMBER,"@fujiisoup Indeed, that seems to be the case. I made a fixed version of `duck_array_ops.where()`, relying on the new `dtypes.result_type()` function that's basically a fixed version of `np.result_type()`.

I believe this is ready for review now.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,290320242
https://github.com/pydata/xarray/pull/1847#issuecomment-364293763,https://api.github.com/repos/pydata/xarray/issues/1847,364293763,MDEyOklzc3VlQ29tbWVudDM2NDI5Mzc2Mw==,6815844,2018-02-09T00:18:52Z,2018-02-09T00:19:33Z,MEMBER,"It looks that our `where` does not do type-casting (inheriting from numpy's where),
```python
In [1]: import numpy as np
   ...: import xarray as xr
   ...: a = xr.Variable('x', np.array(['a', 'b', 'c']))

In [2]: a._getitem_with_mask([1, 2, -1])
Out[2]:
<xarray.Variable (x: 3)>
array(['b', 'c', 'nan'],
      dtype='<U32')
```
nan is converted to string.

I guess we need to cast arrays manually in `_getitem_with_mask` before `where` is applied.
```python
In [9]: dtype, fill_value = xr.core.dtypes.maybe_promote(a.dtype)
   ...: a.astype(dtype)._getitem_with_mask([1, 2, -1])
Out[9]: 
<xarray.Variable (x: 3)>
array(['b', 'c', nan], dtype=object)
```

","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,290320242