issue_comments: 207000636

This data as json

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/818#issuecomment-207000636 https://api.github.com/repos/pydata/xarray/issues/818 207000636 MDEyOklzc3VlQ29tbWVudDIwNzAwMDYzNg== 1197350 2016-04-07T17:14:55Z 2016-04-07T17:14:55Z MEMBER

My new commit supports unstacking in apply with shortcut=True. However, the behavior is kind of weird, in a way that is unique to the multidimensional case.

Consider the behavior of the text case:

``` python

da = xr.DataArray([[0,1],[2,3]], coords={'lon': (['ny','nx'], [[30,40],[40,50]] ), 'lat': (['ny','nx'], [[10,10],[20,20]] ),}, dims=['ny','nx'], da.groupby('lon').apply(lambda x : x - x.mean(), shortcut=False) <xarray.DataArray (lon_groups: 3, ny: 2, nx: 2)> array([[[ 0. , nan], [ nan, nan]],

   [[ nan, -0.5],
    [ 0.5,  nan]],

   [[ nan,  nan],
    [ nan,  0. ]]])

Coordinates: * ny (ny) int64 0 1 * nx (nx) int64 0 1 lat (lon_groups, ny, nx) float64 10.0 nan nan nan nan 10.0 20.0 ... lon (lon_groups, ny, nx) float64 30.0 nan nan nan nan 40.0 40.0 ... * lon_groups (lon_groups) int64 30 40 50 ```

When unstacking, the indices that are not part of the group get filled with nans. We are not able to put these arrays back together into a single array.

Note that if we do not rename the group name here: https://github.com/pydata/xarray/pull/818/files#diff-96b65e0bfec9fd2b9d562483f53661f5R121

Then we get an error here: https://github.com/pydata/xarray/pull/818/files#diff-96b65e0bfec9fd2b9d562483f53661f5R407

ValueError: the variable 'lon' has the same name as one of its dimensions ('lon', 'ny', 'nx'), but it is not 1-dimensional and thus it is not a valid index

 
{
    "total_count": 0,
    "+1": 0,
    "-1": 0,
    "laugh": 0,
    "hooray": 0,
    "confused": 0,
    "heart": 0,
    "rocket": 0,
    "eyes": 0
}
   146182176