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/1042#issuecomment-344386257,https://api.github.com/repos/pydata/xarray/issues/1042,344386257,MDEyOklzc3VlQ29tbWVudDM0NDM4NjI1Nw==,2443309,2017-11-14T20:23:22Z,2017-11-14T20:23:22Z,MEMBER,@chris-b1 - I think you're seeing the issue described in #757. ,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,181881219
https://github.com/pydata/xarray/issues/1042#issuecomment-257814934,https://api.github.com/repos/pydata/xarray/issues/1042,257814934,MDEyOklzc3VlQ29tbWVudDI1NzgxNDkzNA==,10050469,2016-11-02T09:34:46Z,2016-11-02T09:34:46Z,MEMBER,"Closed via https://github.com/pydata/xarray/pull/1049
","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,181881219
https://github.com/pydata/xarray/issues/1042#issuecomment-253936119,https://api.github.com/repos/pydata/xarray/issues/1042,253936119,MDEyOklzc3VlQ29tbWVudDI1MzkzNjExOQ==,1217238,2016-10-14T22:35:56Z,2016-10-14T22:35:56Z,MEMBER,"So the tricky part here is that it's not obvious what is breaking here. One clue is that reducing doesn't seem to be necessary -- I can reproduce this just with applying an identity transform:

```
In [6]: identity = lambda x: x

In [7]: ds.groupby('t').apply(identity)
Out[7]:
<xarray.Dataset>
Dimensions:  (t: 10)
Coordinates:
  * t        (t) int64 0 1 2 3 4 5 6 7 8 9
Data variables:
    a        (t) int64 0 1 2 3 4 5 6 7 8 9
    c        (t) int64 0 1 2 3 4 5 6 7 8 9
    b        (t) int64 0 1 2 3 4 5 6 7 8 9
```

Actually, it looks like it's probably a `concat` bug:

```
In [17]: gb = ds.groupby('t')

In [18]: grouped = [v for _, v in gb]

In [20]: [list(g.data_vars) for g in grouped]
Out[20]:
[['a', 'b', 'c'],
 ['a', 'b', 'c'],
 ['a', 'b', 'c'],
 ['a', 'b', 'c'],
 ['a', 'b', 'c'],
 ['a', 'b', 'c'],
 ['a', 'b', 'c'],
 ['a', 'b', 'c'],
 ['a', 'b', 'c'],
 ['a', 'b', 'c']]

In [21]: xr.concat(grouped, dim='t')
Out[21]:
<xarray.Dataset>
Dimensions:  (t: 10)
Coordinates:
  * t        (t) int64 0 1 2 3 4 5 6 7 8 9
Data variables:
    a        (t) int64 0 1 2 3 4 5 6 7 8 9
    c        (t) int64 0 1 2 3 4 5 6 7 8 9
    b        (t) int64 0 1 2 3 4 5 6 7 8 9
```
","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,181881219
https://github.com/pydata/xarray/issues/1042#issuecomment-253932983,https://api.github.com/repos/pydata/xarray/issues/1042,253932983,MDEyOklzc3VlQ29tbWVudDI1MzkzMjk4Mw==,10050469,2016-10-14T22:16:37Z,2016-10-14T22:16:37Z,MEMBER,"@shoyer I'd be happy to provide a fix if you want. Could you give a short pointer as to where the logic is implemented?
","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,181881219
https://github.com/pydata/xarray/issues/1042#issuecomment-252506038,https://api.github.com/repos/pydata/xarray/issues/1042,252506038,MDEyOklzc3VlQ29tbWVudDI1MjUwNjAzOA==,10050469,2016-10-09T19:13:49Z,2016-10-09T19:13:49Z,MEMBER,"Thanks @shoyer , here's a mwe:

``` python
import xarray as xr
import numpy as np 
ds = xr.Dataset()
for vn in ['a', 'b', 'c']:
    ds[vn] = xr.DataArray(np.arange(10), dims=['t'])
ds.groupby('t').mean()

<xarray.Dataset>
Dimensions:  (t: 10)
Coordinates:
  * t        (t) int64 0 1 2 3 4 5 6 7 8 9
Data variables:
    a        (t) float64 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
    c        (t) float64 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
    b        (t) float64 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
```
","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,181881219
https://github.com/pydata/xarray/issues/1042#issuecomment-252505663,https://api.github.com/repos/pydata/xarray/issues/1042,252505663,MDEyOklzc3VlQ29tbWVudDI1MjUwNTY2Mw==,1217238,2016-10-09T19:06:39Z,2016-10-09T19:06:39Z,MEMBER,"This is probably a bug. Usually, we're pretty careful to always use `OrderedDict` internally for exactly this reason. Can you give a reproducible example?
","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,181881219