issues

What happened?

For a DataArray with no positive values, the plot.contourf() fails to produce the correct figure. It makes the contourf plot and returns successfully, but emits several warnings and does not complete the colorbar. Two sample screenshots are in \

below.

The plot.contour() function has the same behavior, but only when add_colorbar=True.

What did you expect to happen?

No response

Minimal Complete Verifiable Example

Python import xarray as XR da = xr.DataArray(np.arange(20).reshape(4,5), dims=('x','y')) da.plot.contourf() # successful (first image below) (da-19).plot.contourf() # fails (second image below)

Relevant log output

```Python

da = xr.DataArray(np.arange(20).reshape(4,5), dims=('x','y'))

da <xarray.DataArray (x: 4, y: 5)> array([[ 0, 1, 2, 3, 4], [ 5, 6, 7, 8, 9], [10, 11, 12, 13, 14], [15, 16, 17, 18, 19]]) Dimensions without coordinates: x, y

da.plot.contourf() # successful (first image below) <matplotlib.contour.QuadContourSet at 0x299dc2940>

(da-18).plot.contourf() # successful <matplotlib.contour.QuadContourSet at 0x299dc2940>

(da-19).plot.contourf() # fails (second image below) <matplotlib.contour.QuadContourSet at 0x299dc2940> ~/miniconda3/envs/plots/lib/python3.9/site-packages/matplotlib/transforms.py:2663: RuntimeWarning: divide by zero encountered in double_scalars y_scale = 1.0 / inh ~/miniconda3/envs/plots/lib/python3.9/site-packages/matplotlib/transforms.py:2665: RuntimeWarning: invalid value encountered in double_scalars [0.0 , y_scale, (-inb*y_scale)], posx and posy should be finite values posx and posy should be finite values posx and posy should be finite values posx and posy should be finite values

da-19 <xarray.DataArray (x: 4, y: 5)> array([[-19, -18, -17, -16, -15], [-14, -13, -12, -11, -10], [ -9, -8, -7, -6, -5], [ -4, -3, -2, -1, 0]]) Dimensions without coordinates: x, y ```

Anything else we need to know?

Screenshots of plots

```python > da.plot.contourf() # successful ``` ```python > (da-19).plot.contourf() # fails ```

Environment

xr.show_versions()

miniconda3/envs/plots/lib/python3.9/site-packages/_distutils_hack/__init__.py:30: UserWarning: Setuptools is replacing distutils. warnings.warn("Setuptools is replacing distutils.") INSTALLED VERSIONS ------------------ commit: None python: 3.9.12 | packaged by conda-forge | (main, Mar 24 2022, 23:25:14) [Clang 12.0.1 ] python-bits: 64 OS: Darwin OS-release: 21.3.0 machine: arm64 processor: arm byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: ('en_US', 'UTF-8') libhdf5: 1.12.1 libnetcdf: 4.8.1 xarray: 2022.3.0 pandas: 1.3.5 numpy: 1.21.5 scipy: 1.7.1 netCDF4: 1.5.7 pydap: None h5netcdf: None h5py: None Nio: None zarr: None cftime: 1.6.0 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: 1.3.4 dask: 2022.03.0 distributed: None matplotlib: 3.5.0 cartopy: 0.20.2 seaborn: None numbagg: None fsspec: 2022.02.0 cupy: None pint: None sparse: None setuptools: 61.2.0 pip: 22.0.4 conda: None pytest: None IPython: 7.29.0 sphinx: None

What happened?

The DataArray.rename API is inconsistent with Dataset.rename and the documentation does not make that obvious.

Unlike Dataset.rename, * A DataArray cannot be renamed using a keyword argument, but fails saying "[name] is not a variable or dimension in this dataset" (example A below). * Passing the new name as a positional argument, but with other keyword arguments fails with the statement "the first argument to .rename must be a dictionary" (example B below). * As a consequence, renaming the array as well as its dimension(s)/coordinate(s) requires two separate function calls, i.e. da.rename("newname").rename("dim_0"="x").

Examples

Start with an array, da, and a dataset, ds ```python

da = xr.DataArray( np.zeros((2,3)), name="alpha", coords={"x":range(2), "y":range(3)} ) da <xarray.DataArray 'alpha' (x: 2, y: 3)> array([[0., 0., 0.], [0., 0., 0.]]) Coordinates: * x (x) int64 0 1 * y (y) int64 0 1 2

ds = xr.Dataset({"alpha":da}) ds <xarray.Dataset> Dimensions: (x: 2, y: 3) Coordinates: * x (x) int64 0 1 * y (y) int64 0 1 2 Data variables: alpha (x, y) float64 0.0 0.0 0.0 0.0 0.0 0.0 ```

Dataset example ds.rename renames everything at once using keyword arguments ```python

ds.rename(x="i", y="j", alpha="beta") <xarray.Dataset> Dimensions: (i: 2, j: 3) Coordinates: * i (i) int64 0 1 * j (j) int64 0 1 2 Data variables: beta (i, j) float64 0.0 0.0 0.0 0.0 0.0 0.0 ```

Example A da.rename does not recognize the array's current name as a keyword and returns a confusing error message. ```python

da.rename(alpha="beta")

ValueError Traceback (most recent call last) <ipython-input-98-af366146dc6f> in <module> ----> 1 da.rename(alpha="beta", x="i")

xarray/core/dataarray.py in rename(self, new_name_or_name_dict, **names) 1842 ) 1843 name_dict = either_dict_or_kwargs(new_name_or_name_dict, names, "rename") -> 1844 dataset = self._to_temp_dataset().rename(name_dict) 1845 return self._from_temp_dataset(dataset) 1846 else:

xarray/core/dataset.py in rename(self, name_dict, **names) 3390 for k in name_dict.keys(): 3391 if k not in self and k not in self.dims: -> 3392 raise ValueError( 3393 f"cannot rename {k!r} because it is not a " 3394 "variable or dimension in this dataset"

ValueError: cannot rename 'alpha' because it is not a variable or dimension in this dataset ```

Example B da.rename will not change the name of the array as well as the dimension(s)/coordinate(s) names and emits an untrue error message, since the array cannot be renamed using a dict. ```python

da.rename("beta", x="i")

ValueError Traceback (most recent call last) <ipython-input-99-f90b078d6bd5> in <module> ----> 1 da.rename("beta", x="i")

xarray/core/dataarray.py in rename(self, new_name_or_name_dict, **names) 1841 Mapping[Hashable, Hashable], new_name_or_name_dict 1842 ) -> 1843 name_dict = either_dict_or_kwargs(new_name_or_name_dict, names, "rename") 1844 dataset = self._to_temp_dataset().rename(name_dict) 1845 return self._from_temp_dataset(dataset)

xarray/core/utils.py in either_dict_or_kwargs(pos_kwargs, kw_kwargs, func_name) 284 285 if not is_dict_like(pos_kwargs): --> 286 raise ValueError(f"the first argument to .{func_name} must be a dictionary") 287 if kw_kwargs: 288 raise ValueError(

ValueError: the first argument to .rename must be a dictionary ```

What did you expect to happen?

No response

Minimal Complete Verifiable Example

No response

Relevant log output

No response

Anything else we need to know?

No response

Environment

INSTALLED VERSIONS

commit: None python: 3.9.10 | packaged by conda-forge | (main, Feb 1 2022, 21:25:34) [Clang 11.1.0 ] python-bits: 64 OS: Darwin OS-release: 21.1.0 machine: arm64 processor: arm byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: ('en_US', 'UTF-8') libhdf5: 1.12.1 libnetcdf: 4.8.1

xarray: 0.21.1 pandas: 1.3.5 numpy: 1.22.2 scipy: 1.7.1 netCDF4: 1.5.7 pydap: None h5netcdf: None h5py: None Nio: None zarr: None cftime: 1.5.2 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: 1.3.2 dask: None distributed: None matplotlib: 3.5.0 cartopy: None seaborn: None numbagg: None fsspec: None cupy: None pint: None sparse: None setuptools: 60.7.1 pip: 22.0.3 conda: None pytest: None IPython: 7.29.0 sphinx: None