id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
166439490,MDU6SXNzdWUxNjY0Mzk0OTA=,906,unstack() sorts data alphabetically,6213168,closed,0,,,14,2016-07-19T21:25:26Z,2019-02-23T12:47:00Z,2019-02-23T12:47:00Z,MEMBER,,,,"DataArray.unstack() sorts the data alphabetically by label.
Besides being poor for performance, this is very problematic whenever the order matters, and the labels are not in alphabetical order to begin with.

``` python

import xarray
import pandas

index = [
    ['x1', 'first' ],
    ['x1', 'second'],
    ['x1', 'third' ],
    ['x1', 'fourth'],
    ['x0', 'first' ],
    ['x0', 'second'],
    ['x0', 'third' ],
    ['x0', 'fourth'],
]
index = pandas.MultiIndex.from_tuples(index, names=['x', 'count'])
s = pandas.Series(list(range(8)), index)
a = xarray.DataArray(s)
a
```

```
<xarray.DataArray (dim_0: 8)>
array([0, 1, 2, 3, 4, 5, 6, 7], dtype=int64)
Coordinates:
  * dim_0    (dim_0) object ('x1', 'first') ('x1', 'second') ('x1', 'third') ...
```

``` python
a.unstack('dim_0')
```

```
<xarray.DataArray (x: 2, count: 4)>
array([[4, 7, 5, 6],
       [0, 3, 1, 2]], dtype=int64)
Coordinates:
  * x        (x) object 'x0' 'x1'
  * count    (count) object 'first' 'fourth' 'second' 'third'
```
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