issues: 657466413

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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
657466413 MDU6SXNzdWU2NTc0NjY0MTM= 4228 to_dataframe: no valid index for a 0-dimensional object 10563614 closed 0     5 2020-07-15T15:58:43Z 2020-10-26T08:42:35Z 2020-10-26T08:42:35Z CONTRIBUTOR      

What happened: xr.DataArray([1], coords=[('onecoord', [2])]).sel(onecoord=2).to_dataframe(name='name') raise an exception ValueError: no valid index for a 0-dimensional object

What you expected to happen:

the same behavior as: xr.DataArray([1], coords=[('onecoord', [2])]).to_dataframe(name='name')

Anything else we need to know?:

I see that the array after the selection has no "dims" anymore, and this is what cause the error. but it still has one "coords", this is confusing. Is there any documentation about this difference ?

Environment:

INSTALLED VERSIONS ------------------ commit: None python: 3.7.6 | packaged by conda-forge | (default, Jun 1 2020, 18:57:50) [GCC 7.5.0] python-bits: 64 OS: Linux OS-release: 4.19.0-9-amd64 machine: x86_64 processor: byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: en_US.UTF-8 libhdf5: 1.10.5 libnetcdf: 4.7.4 xarray: 0.15.1 pandas: 1.0.4 numpy: 1.18.5 scipy: 1.4.1 netCDF4: 1.5.3 pydap: None h5netcdf: None h5py: 2.10.0 Nio: None zarr: 2.4.0 cftime: 1.1.3 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: 1.3.2 dask: 2.18.1 distributed: 2.18.0 matplotlib: 3.2.1 cartopy: None seaborn: 0.10.1 numbagg: None setuptools: 47.3.1.post20200616 pip: 20.1.1 conda: 4.8.3 pytest: 5.4.3 IPython: 7.15.0 sphinx: 3.1.1 
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   completed 13221727 issue

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