What happened?

When calling reset_coords on a dataset that is loaded from disk, the coordinates are not removed from the encoding of the variable.

This means, that at save time they will be resaved as coordinates... annoying. (and erroneous)

What did you expect to happen?

No response

Minimal Complete Verifiable Example

```Python import xarray as xr

dataset = xr.Dataset( data_vars={'images': (('y', 'x'), np.zeros((10, 2)))}, coords={'zar': 1} )

dataset.to_netcdf('foo.nc', mode='w')

%%

foo_loaded = xr.open_dataset('foo.nc')

foo_loaded_reset = foo_loaded.reset_coords()

%%

assert 'zar' in foo_loaded.coords assert 'zar' not in foo_loaded_reset.coords assert 'zar' in foo_loaded_reset.data_vars foo_loaded_reset.to_netcdf('bar.nc', mode='w')

%% Now load the dataset

bar_loaded = xr.open_dataset('bar.nc') assert 'zar' not in bar_loaded.coords, 'zar is erroneously a coordinate'

%%

This is the problem

assert 'zar' not in foo_loaded_reset.images.encoding['coordinates'].split(' '), "zar should not be in here" ```

MVCE confirmation

• [X] Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• [X] Complete example — the example is self-contained, including all data and the text of any traceback.
• [X] Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• [X] New issue — a search of GitHub Issues suggests this is not a duplicate.

Relevant log output

No response

Anything else we need to know?

for _, variable in obj._variables.items(): coords_in_encoding = set(variable.encoding.get('coordinates', ' ').split(' ')) variable.encoding['coordinates'] = ' '.join(coords_in_encoding - set(names)) suggested fix in dataset.py, reset_coords

https://github.com/pydata/xarray/blob/513ee34f16cc8f9250a72952e33bf9b4c95d33d1/xarray/core/dataset.py#L1734

Environment

``` INSTALLED VERSIONS ------------------ commit: None python: 3.9.13 | packaged by Ramona Optics | (main, Aug 31 2022, 22:30:30) [GCC 10.4.0] python-bits: 64 OS: Linux OS-release: 5.15.0-50-generic machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: ('en_US', 'UTF-8') libhdf5: 1.12.2 libnetcdf: 4.8.1 xarray: 2022.10.0 pandas: 1.5.1 numpy: 1.23.4 scipy: 1.9.3 netCDF4: 1.6.1 pydap: None h5netcdf: 1.0.2 h5py: 3.7.0 Nio: None zarr: 2.13.3 cftime: 1.6.2 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: None dask: 2022.10.0 distributed: 2022.10.0 matplotlib: 3.6.1 cartopy: None seaborn: None numbagg: None fsspec: 2022.10.0 cupy: None pint: 0.20.1 sparse: None flox: None numpy_groupies: None setuptools: 65.5.0 pip: 22.3 conda: 22.9.0 pytest: 7.2.0 IPython: 7.33.0 sphinx: 5.3.0 /home/mark/mambaforge/envs/mcam_dev/lib/python3.9/site-packages/_distutils_hack/__init__.py:33: UserWarning: Setuptools is replacing distutils. warnings.warn("Setuptools is replacing distutils.") ```