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/1352#issuecomment-292929325,https://api.github.com/repos/pydata/xarray/issues/1352,292929325,MDEyOklzc3VlQ29tbWVudDI5MjkyOTMyNQ==,358378,2017-04-10T12:02:09Z,2017-04-10T12:02:09Z,CONTRIBUTOR,"Thanks, @darothen ! However, I believe I shouldn't *have to*, but xarray should do the right thing automatically.

Maybe I want to use the dataset after saving for something else, which would mean I'd have to do something like `d_.drop(['category', 'species']).to_netcdf(...)`, which I don't like too much ...","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,219321876
https://github.com/pydata/xarray/issues/1352#issuecomment-292873315,https://api.github.com/repos/pydata/xarray/issues/1352,292873315,MDEyOklzc3VlQ29tbWVudDI5Mjg3MzMxNQ==,358378,2017-04-10T07:42:02Z,2017-04-10T07:42:02Z,CONTRIBUTOR,"Sure :smile:

I first open a DataArray:

    grid_eu_coarse_noborder = xr.open_dataarray('tno-macc3_eu-no-nld-no-border_area.nc')
    grid_eu_coarse_noborder

    <xarray.DataArray 'TNO-MACC3_EU' (species: 12, category: 15, lon: 720, lat: 672)>
    [87091200 values with dtype=float64]
    Coordinates:
      * lat       (lat) float64 30.03 30.09 30.16 30.22 30.28 30.34 30.41 30.47 ...
      * category  (category) object 'pow' 'res' 'inc' 'pei' 'exf' 'sol' 'tra1' ...
      * species   (species) object 'CH4' 'CO' 'NH3' 'NMVOC' 'NOX' 'BC_1' ...
      * lon       (lon) float64 -29.94 -29.81 -29.69 -29.56 -29.44 -29.31 -29.19 ...

from which I select using `.loc[]` and convert to Dataset:

    grid_eu_coarse_noborder.loc['NOX', 'pow'].to_dataset()

    <xarray.Dataset>
    Dimensions:       (lat: 672, lon: 720)
    Coordinates:
      * lat           (lat) float64 30.03 30.09 30.16 30.22 30.28 30.34 30.41 ...
        category      <U3 'pow'
        species       <U3 'NOX'
      * lon           (lon) float64 -29.94 -29.81 -29.69 -29.56 -29.44 -29.31 ...
    Data variables:
        TNO-MACC3_EU  (lon, lat) float64 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ...

which then cannot be saved:

    grid_eu_coarse_noborder.loc['NOX', 'pow'].to_dataset().to_netcdf('test.nc')


    ---------------------------------------------------------------------------
    IndexError                                Traceback (most recent call last)
    /home/eb/software/LAMOSpy/0.2-intel-2016a-Python-3.5.1/lib/python3.5/site-packages/xarray-0.9.1-py3.5.egg/xarray/core/utils.py in __len__(self)
        395         try:
    --> 396             return self.shape[0]
        397         except IndexError:
    
    IndexError: tuple index out of range
    
    During handling of the above exception, another exception occurred:
    
    TypeError                                 Traceback (most recent call last)
    <ipython-input-8-fb260f3bec4b> in <module>()
    ----> 1 grid_eu_coarse_noborder.loc['NOX', 'pow'].to_dataset().to_netcdf('test.nc')
    
    /home/eb/software/LAMOSpy/0.2-intel-2016a-Python-3.5.1/lib/python3.5/site-packages/xarray-0.9.1-py3.5.egg/xarray/core/dataset.py in to_netcdf(self, path, mode, format, group, engine, encoding, unlimited_dims)
        951         return to_netcdf(self, path, mode, format=format, group=group,
        952                          engine=engine, encoding=encoding,
    --> 953                          unlimited_dims=unlimited_dims)
        954 
        955     def __unicode__(self):
    
    /home/eb/software/LAMOSpy/0.2-intel-2016a-Python-3.5.1/lib/python3.5/site-packages/xarray-0.9.1-py3.5.egg/xarray/backends/api.py in to_netcdf(dataset, path, mode, format, group, engine, writer, encoding, unlimited_dims)
        567     try:
        568         dataset.dump_to_store(store, sync=sync, encoding=encoding,
    --> 569                               unlimited_dims=unlimited_dims)
        570         if isinstance(path, BytesIO):
        571             return path.getvalue()
    
    /home/eb/software/LAMOSpy/0.2-intel-2016a-Python-3.5.1/lib/python3.5/site-packages/xarray-0.9.1-py3.5.egg/xarray/core/dataset.py in dump_to_store(self, store, encoder, sync, encoding, unlimited_dims)
        891 
        892         store.store(variables, attrs, check_encoding,
    --> 893                     unlimited_dims=unlimited_dims)
        894         if sync:
        895             store.sync()
    
    /home/eb/software/LAMOSpy/0.2-intel-2016a-Python-3.5.1/lib/python3.5/site-packages/xarray-0.9.1-py3.5.egg/xarray/backends/common.py in store(self, variables, attributes, *args, **kwargs)
        233         cf_variables, cf_attrs = cf_encoder(variables, attributes)
        234         AbstractWritableDataStore.store(self, cf_variables, cf_attrs,
    --> 235                                         *args, **kwargs)
        236 
        237 
    
    /home/eb/software/LAMOSpy/0.2-intel-2016a-Python-3.5.1/lib/python3.5/site-packages/xarray-0.9.1-py3.5.egg/xarray/backends/common.py in store(self, variables, attributes, check_encoding_set, unlimited_dims)
        202         self.set_attributes(attributes)
        203         self.set_variables(variables, check_encoding_set,
    --> 204                            unlimited_dims=unlimited_dims)
        205 
        206     def set_attributes(self, attributes):
    
    /home/eb/software/LAMOSpy/0.2-intel-2016a-Python-3.5.1/lib/python3.5/site-packages/xarray-0.9.1-py3.5.egg/xarray/backends/common.py in set_variables(self, variables, check_encoding_set, unlimited_dims)
        214             check = vn in check_encoding_set
        215             target, source = self.prepare_variable(
    --> 216                 name, v, check, unlimited_dims=unlimited_dims)
        217             self.writer.add(source, target)
        218 
    
    /home/eb/software/LAMOSpy/0.2-intel-2016a-Python-3.5.1/lib/python3.5/site-packages/xarray-0.9.1-py3.5.egg/xarray/backends/netCDF4_.py in prepare_variable(self, name, variable, check_encoding, unlimited_dims)
        272 
        273         if self.format == 'NETCDF4':
    --> 274             variable, datatype = _nc4_values_and_dtype(variable)
        275         else:
        276             variable = encode_nc3_variable(variable)
    
    /home/eb/software/LAMOSpy/0.2-intel-2016a-Python-3.5.1/lib/python3.5/site-packages/xarray-0.9.1-py3.5.egg/xarray/backends/netCDF4_.py in _nc4_values_and_dtype(var)
         78     if var.dtype.kind == 'U':
         79         # this entire clause should not be necessary with netCDF4>=1.0.9
    ---> 80         if len(var) > 0:
         81             var = var.astype('O')
         82         dtype = str
    
    /home/eb/software/LAMOSpy/0.2-intel-2016a-Python-3.5.1/lib/python3.5/site-packages/xarray-0.9.1-py3.5.egg/xarray/core/utils.py in __len__(self)
        396             return self.shape[0]
        397         except IndexError:
    --> 398             raise TypeError('len() of unsized object')
        399 
        400 
    
    TypeError: len() of unsized object
","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,219321876