What happened?

python ds.plot.scatter("x","y")

returns:

```python

KeyError Traceback (most recent call last) File /autofs/nas1/home/isimoesdesousa/programs/mambaforge/envs/coringa/lib/python3.9/site-packages/xarray/core/dataset.py:1340, in Dataset._construct_dataarray(self, name) 1339 try: -> 1340 variable = self._variables[name] 1341 except KeyError:

KeyError: None

During handling of the above exception, another exception occurred:

KeyError Traceback (most recent call last) Cell In[60], line 1 ----> 1 ds.plot.scatter("x","y")

File /autofs/nas1/home/isimoesdesousa/programs/mambaforge/envs/coringa/lib/python3.9/site-packages/xarray/plot/accessor.py:1071, in DatasetPlotAccessor.scatter(self, args, kwargs) 1069 @functools.wraps(dataset_plot.scatter) 1070 def scatter(self, args, kwargs) -> PathCollection | FacetGrid[DataArray]: -> 1071 return dataset_plot.scatter(self._ds, *args, kwargs)

File /autofs/nas1/home/isimoesdesousa/programs/mambaforge/envs/coringa/lib/python3.9/site-packages/xarray/plot/dataset_plot.py:914, in scatter(ds, x, y, z, hue, hue_style, markersize, linewidth, figsize, size, aspect, ax, row, col, col_wrap, xincrease, yincrease, add_legend, add_colorbar, add_labels, add_title, subplot_kws, xscale, yscale, xticks, yticks, xlim, ylim, cmap, vmin, vmax, norm, extend, levels, args, kwargs) 912 del locals_["ds"] 913 locals_.update(locals_.pop("kwargs", {})) --> 914 da = temp_dataarray(ds, y, locals) 916 return da.plot.scatter(locals_.pop("args", ()), **locals_)

File /autofs/nas1/home/isimoesdesousa/programs/mambaforge/envs/coringa/lib/python3.9/site-packages/xarray/plot/dataset_plot.py:740, in temp_dataarray(ds, y, locals) 736 coords[key] = ds[key] 738 # The dataarray has to include all the dims. Broadcast to that shape 739 # and add the additional coords: --> 740 _y = ds[y].broadcast_like(ds) 742 return DataArray(_y, coords=coords)

File /autofs/nas1/home/isimoesdesousa/programs/mambaforge/envs/coringa/lib/python3.9/site-packages/xarray/core/dataset.py:1431, in Dataset.getitem(self, key) 1429 return self.isel(**key) 1430 if utils.hashable(key): -> 1431 return self._construct_dataarray(key) 1432 if utils.iterable_of_hashable(key): 1433 return self._copy_listed(key)

File /autofs/nas1/home/isimoesdesousa/programs/mambaforge/envs/coringa/lib/python3.9/site-packages/xarray/core/dataset.py:1342, in Dataset.construct_dataarray(self, name) 1340 variable = self._variables[name] 1341 except KeyError: -> 1342 , name, variable = _get_virtual_variable(self._variables, name, self.dims) 1344 needed_dims = set(variable.dims) 1346 coords: dict[Hashable, Variable] = {}

File /autofs/nas1/home/isimoesdesousa/programs/mambaforge/envs/coringa/lib/python3.9/site-packages/xarray/core/dataset.py:174, in _get_virtual_variable(variables, key, dim_sizes) 171 return key, key, variable 173 if not isinstance(key, str): --> 174 raise KeyError(key) 176 split_key = key.split(".", 1) 177 if len(split_key) != 2:

KeyError: None ```

What did you expect to happen?

To plot the figure:

Minimal Complete Verifiable Example

```Python import pandas as pd

n = 1000 df = pd.DataFrame() df["x"] = np.random.randn(n) df["y"] = np.random.randn(n) ds = df.to_xarray()

this works

ds.plot.scatter(x="x",y="y")

this doesn't work

ds.plot.scatter("x","y") ```

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?

No response

Environment

NSTALLED VERSIONS ------------------ commit: None python: 3.9.15 | packaged by conda-forge | (main, Nov 22 2022, 15:55:03) [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: 2022.12.0 pandas: 1.5.2 numpy: 1.24.0 scipy: 1.9.3 netCDF4: 1.6.2 pydap: None h5netcdf: None h5py: None Nio: None zarr: None cftime: 1.6.2 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: 1.3.5 dask: 2022.12.1 distributed: 2022.12.1 matplotlib: 3.6.2 cartopy: None seaborn: None numbagg: None fsspec: 2022.11.0 cupy: None pint: None sparse: None flox: None numpy_groupies: None setuptools: 65.6.3 pip: 22.3.1 conda: None pytest: None mypy: None IPython: 8.7.0 sphinx: None