Dataset.mean drops coordinates

[ignamv]

Hi,

Dataset.mean drops coordinates, unlike DataArray.mean:

x = xarray.DataArray([2., 4.], 
                     coords={'a':[1., 2.], 'b': 3.}, 
                     dims=['a'],
                     name='name')
print 'DataArray mean:'
print x.mean(dim='a')
print 'Dataset mean:'
print x.to_dataset().mean(dim='a')['name']

Output

DataArray mean
<xarray.DataArray 'name' ()>
array(3.0)
Coordinates:
    b        float64 3.0
Dataset mean
<xarray.DataArray 'name' ()>
array(3.0)

Thanks
Ignacio

[shoyer]

Thanks for the report.

I'm marking this as a bug: I think we should probably keep the extra coordinates in both cases, but it should certainly be consistent.