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https://github.com/pydata/xarray/issues/2550#issuecomment-437161279 https://api.github.com/repos/pydata/xarray/issues/2550 437161279 MDEyOklzc3VlQ29tbWVudDQzNzE2MTI3OQ== 4806877 2018-11-08T21:24:45Z 2018-11-08T21:24:45Z CONTRIBUTOR

@jhamman that looks pretty good, but I'm not seeing the source in the encoding dict. Is this what you were expecting?

```python def func(ds): var = next(var for var in ds) return ds.assign(path=ds[var].encoding['source'])

xr.open_mfdataset(['./ST4.2018092500.01h', './ST4.2018092501.01h'], engine='pynio', concat_dim='path', preprocess=func) python-traceback

KeyError Traceback (most recent call last) <ipython-input-49-184da62ce353> in <module>() ----> 1 ds = xr.open_mfdataset(['./ST4.2018092500.01h', './ST4.2018092501.01h'], engine='pynio', concat_dim='path', preprocess=func)

/opt/conda/lib/python3.6/site-packages/xarray/backends/api.py in open_mfdataset(paths, chunks, concat_dim, compat, preprocess, engine, lock, data_vars, coords, autoclose, parallel, **kwargs) 612 file_objs = [getattr_(ds, '_file_obj') for ds in datasets] 613 if preprocess is not None: --> 614 datasets = [preprocess(ds) for ds in datasets] 615 616 if parallel:

/opt/conda/lib/python3.6/site-packages/xarray/backends/api.py in <listcomp>(.0) 612 file_objs = [getattr_(ds, '_file_obj') for ds in datasets] 613 if preprocess is not None: --> 614 datasets = [preprocess(ds) for ds in datasets] 615 616 if parallel:

<ipython-input-48-fd450fa1393a> in func(ds) 1 def func(ds): 2 var = next(var for var in ds) ----> 3 return ds.assign(path=ds[var].encoding['source'])

KeyError: 'source' ```

xarray version: '0.11.0+1.g575e97ae'

 
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