issues: 94030797

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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
94030797 MDU6SXNzdWU5NDAzMDc5Nw== 458 groupby / apply and dask (`open_mfdataset`) 1177508 closed 0     2 2015-07-09T12:10:04Z 2015-07-15T00:02:40Z 2015-07-15T00:02:34Z NONE      

It seems that, when working with open_mfdataset, things are not consistent. Trying the following:

python import numpy as np import xray a = xray.open_mfdataset('*.nc', concat_dim='time', preprocess=lambda x: x.assign_coords(agl=('mean_height_agl', range(x.dims['mean_height_agl']))).swap_dims({'mean_height_agl': 'agl'}).squeeze('time')) a.groupby('time').apply(np.sum)

gives an error with a huge traceback that ends with:

``` python IndexError: Exception in remote process

tuple index out of range

Traceback: File "/home/razvan/.local/lib/python3.4/site-packages/dask/async.py", line 260, in execute_task result = _execute_task(task, data) File "/home/razvan/.local/lib/python3.4/site-packages/dask/async.py", line 243, in _execute_task return func(*args2) File "/home/razvan/.local/lib/python3.4/site-packages/toolz/functoolz.py", line 378, in call ret = fns0 File "/home/razvan/.local/lib/python3.4/site-packages/dask/array/core.py", line 377, in _concatenate2 ```

but if I do:

python a.load() a.groupby('time').apply(np.sum)

there's no error. The files I'm using for this are at this dropbox place.

 
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