issues: 1342272827

What happened?

I am encountering an error while attempting to plot xarray fields using cartopy & matplotlib. [I'm posting here first but I'm not sure if the error is due to xarray, cartopy, or matplotlib].

What did you expect to happen?

Here is an example of the error using a plot from @rabernat's course: https://earth-env-data-science.github.io/lectures/mapping_cartopy.html#xarray-integration

Minimal Complete Verifiable Example

Python import cartopy.crs as ccrs import matplotlib.pyplot as plt import xarray as xr url = 'http://www.esrl.noaa.gov/psd/thredds/dodsC/Datasets/noaa.ersst.v5/sst.mnmean.nc' ds = xr.open_dataset(url, drop_variables=['time_bnds']) sst = ds.sst.sel(time='2000-01-01', method='nearest') fig = plt.figure(figsize=(9,6)) ax = plt.axes(projection=ccrs.Robinson()) ax.coastlines() ax.gridlines() sst.plot(ax=ax, transform=ccrs.PlateCarree(), vmin=2, vmax=30)

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

```Python TypeError Traceback (most recent call last) Input In [12], in <cell line: 11>() 9 ax.coastlines() 10 ax.gridlines() ---> 11 sst.plot(ax=ax, transform=ccrs.PlateCarree(), 12 vmin=2, vmax=30)

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/xarray/plot/plot.py:868, in _PlotMethods.call(self, kwargs) 867 def call(self, kwargs): --> 868 return plot(self._da, **kwargs)

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/xarray/plot/plot.py:334, in plot(darray, row, col, col_wrap, ax, hue, rtol, subplot_kws, kwargs) 330 plotfunc = hist 332 kwargs["ax"] = ax --> 334 return plotfunc(darray, kwargs)

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/xarray/plot/plot.py:1212, in _plot2d.<locals>.newplotfunc(darray, x, y, figsize, size, aspect, ax, row, col, col_wrap, xincrease, yincrease, add_colorbar, add_labels, vmin, vmax, cmap, center, robust, extend, levels, infer_intervals, colors, subplot_kws, cbar_ax, cbar_kwargs, xscale, yscale, xticks, yticks, xlim, ylim, norm, kwargs) 1208 raise ValueError("plt.imshow's aspect kwarg is not available in xarray") 1210 ax = get_axis(figsize, size, aspect, ax, subplot_kws) -> 1212 primitive = plotfunc( 1213 xplt, 1214 yplt, 1215 zval, 1216 ax=ax, 1217 cmap=cmap_params["cmap"], 1218 vmin=cmap_params["vmin"], 1219 vmax=cmap_params["vmax"], 1220 norm=cmap_params["norm"], 1221 **kwargs, 1222 ) 1224 # Label the plot with metadata 1225 if add_labels:

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/xarray/plot/plot.py:1478, in pcolormesh(x, y, z, ax, xscale, yscale, infer_intervals, kwargs) 1475 y = _infer_interval_breaks(y, axis=1, scale=yscale) 1476 y = _infer_interval_breaks(y, axis=0, scale=yscale) -> 1478 primitive = ax.pcolormesh(x, y, z, kwargs) 1480 # by default, pcolormesh picks "round" values for bounds 1481 # this results in ugly looking plots with lots of surrounding whitespace 1482 if not hasattr(ax, "projection") and x.ndim == 1 and y.ndim == 1: 1483 # not a cartopy geoaxis

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/mpl/geoaxes.py:318, in _add_transform.<locals>.wrapper(self, args, kwargs) 313 raise ValueError(f'Invalid transform: Spherical {func.name} ' 314 'is not supported - consider using ' 315 'PlateCarree/RotatedPole.') 317 kwargs['transform'] = transform --> 318 return func(self, args, **kwargs)

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/mpl/geoaxes.py:1799, in GeoAxes.pcolormesh(self, args, kwargs) 1797 result = matplotlib.axes.Axes.pcolormesh(self, args, kwargs) 1798 # Wrap the quadrilaterals if necessary -> 1799 result = self._wrap_quadmesh(result, kwargs) 1800 # Re-cast the QuadMesh as a GeoQuadMesh to enable future wrapping 1801 # updates to the collection as well. 1802 result.class = cartopy.mpl.geocollection.GeoQuadMesh

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/mpl/geoaxes.py:1982, in GeoAxes._wrap_quadmesh(self, collection, kwargs) 1968 # Plot all of the wrapped cells. 1969 # pcolor only draws polygons where the data is not 1970 # masked, so this will only draw a limited subset of (...) 1978 # fill in the proper data later with set_array() 1979 # calls. 1980 pcolor_data = np.ma.array(np.zeros(C.shape), 1981 mask=~mask) -> 1982 pcolor_col = self.pcolor(coords[..., 0], coords[..., 1], 1983 pcolor_data, zorder=zorder, 1984 kwargs) 1985 # Now add back in the masked data if there was any 1986 full_mask = ~mask if C_mask is None else ~mask | C_mask

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/mpl/geoaxes.py:318, in _add_transform.<locals>.wrapper(self, args, kwargs) 313 raise ValueError(f'Invalid transform: Spherical {func.name} ' 314 'is not supported - consider using ' 315 'PlateCarree/RotatedPole.') 317 kwargs['transform'] = transform --> 318 return func(self, args, **kwargs)

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/mpl/geoaxes.py:2027, in GeoAxes.pcolor(self, args, kwargs) 2024 result = matplotlib.axes.Axes.pcolor(self, args, **kwargs) 2026 # Update the datalim for this pcolor. -> 2027 limits = result.get_datalim(self.transData) 2028 self.update_datalim(limits) 2030 self.autoscale_view()

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/collections.py:280, in Collection.get_datalim(self, transData) 277 return transforms.Bbox.null() 279 if not transform.is_affine: --> 280 paths = [transform.transform_path_non_affine(p) for p in paths] 281 # Don't convert transform to transform.get_affine() here because 282 # we may have transform.contains_branch(transData) but not 283 # transforms.get_affine().contains_branch(transData). But later, 284 # be careful to only apply the affine part that remains. 286 if any(transform.contains_branch_seperately(transData)):

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/collections.py:280, in <listcomp>(.0) 277 return transforms.Bbox.null() 279 if not transform.is_affine: --> 280 paths = [transform.transform_path_non_affine(p) for p in paths] 281 # Don't convert transform to transform.get_affine() here because 282 # we may have transform.contains_branch(transData) but not 283 # transforms.get_affine().contains_branch(transData). But later, 284 # be careful to only apply the affine part that remains. 286 if any(transform.contains_branch_seperately(transData)):

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/transforms.py:2436, in CompositeGenericTransform.transform_path_non_affine(self, path) 2434 return path 2435 elif not self._a.is_affine and self._b.is_affine: -> 2436 return self._a.transform_path_non_affine(path) 2437 else: 2438 return self._b.transform_path_non_affine( 2439 self._a.transform_path(path))

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/mpl/geoaxes.py:190, in InterProjectionTransform.transform_path_non_affine(self, src_path) 186 geoms = cpatch.path_to_geos(src_path, 187 getattr(self, 'force_path_ccw', False)) 189 for geom in geoms: --> 190 proj_geom = self.target_projection.project_geometry( 191 geom, self.source_projection) 192 transformed_geoms.append(proj_geom) 194 if not transformed_geoms:

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/crs.py:805, in Projection.project_geometry(self, geometry, src_crs) 803 if not method_name: 804 raise ValueError(f'Unsupported geometry type {geom_type!r}') --> 805 return getattr(self, method_name)(geometry, src_crs)

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/crs.py:948, in Projection._project_polygon(self, polygon, src_crs) 946 multi_lines = [] 947 for src_ring in [polygon.exterior] + list(polygon.interiors): --> 948 p_rings, p_mline = self._project_linear_ring(src_ring, src_crs) 949 if p_rings: 950 rings.extend(p_rings)

File ~/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/crs.py:824, in Projection._project_linear_ring(self, linear_ring, src_crs) 819 debug = False 820 # 1) Resolve the initial lines into projected segments 821 # 1abc 822 # def23ghi 823 # jkl41 --> 824 multi_line_string = cartopy.trace.project_linear(linear_ring, 825 src_crs, self) 827 # Threshold for whether a point is close enough to be the same 828 # point as another. 829 threshold = max(np.abs(self.x_limits + self.y_limits)) * 1e-5

File lib/cartopy/trace.pyx:628, in cartopy.trace.project_linear()

File lib/cartopy/trace.pyx:100, in cartopy.trace.geos_from_shapely()

TypeError: an integer is required

Exception in Tkinter callback Traceback (most recent call last): File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/tkinter/init.py", line 1921, in call return self.func(args) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/tkinter/init.py", line 839, in callit func(args) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/backends/_backend_tk.py", line 252, in idle_draw self.draw() File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/backends/backend_tkagg.py", line 9, in draw super().draw() File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/backends/backend_agg.py", line 436, in draw self.figure.draw(self.renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 74, in draw_wrapper result = draw(artist, renderer, args, kwargs) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/figure.py", line 2845, in draw mimage._draw_list_compositing_images( File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/image.py", line 132, in _draw_list_compositing_images a.draw(renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/mpl/geoaxes.py", line 558, in draw return matplotlib.axes.Axes.draw(self, renderer=renderer, kwargs) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/axes/_base.py", line 3091, in draw mimage._draw_list_compositing_images( File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/image.py", line 132, in _draw_list_compositing_images a.draw(renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/collections.py", line 990, in draw super().draw(renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/collections.py", line 366, in draw transform, transOffset, offsets, paths = self._prepare_points() File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/collections.py", line 343, in _prepare_points paths = [transform.transform_path_non_affine(path) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/collections.py", line 343, in <listcomp> paths = [transform.transform_path_non_affine(path) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/transforms.py", line 2436, in transform_path_non_affine return self._a.transform_path_non_affine(path) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/mpl/geoaxes.py", line 190, in transform_path_non_affine proj_geom = self.target_projection.project_geometry( File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/crs.py", line 805, in project_geometry return getattr(self, method_name)(geometry, src_crs) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/crs.py", line 948, in _project_polygon p_rings, p_mline = self._project_linear_ring(src_ring, src_crs) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/crs.py", line 824, in _project_linear_ring multi_line_string = cartopy.trace.project_linear(linear_ring, File "lib/cartopy/trace.pyx", line 628, in cartopy.trace.project_linear File "lib/cartopy/trace.pyx", line 100, in cartopy.trace.geos_from_shapely TypeError: an integer is required Exception in Tkinter callback Traceback (most recent call last): File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/tkinter/init.py", line 1921, in call return self.func(args) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/tkinter/init.py", line 839, in callit func(args) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/backends/_backend_tk.py", line 252, in idle_draw self.draw() File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/backends/backend_tkagg.py", line 9, in draw super().draw() File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/backends/backend_agg.py", line 436, in draw self.figure.draw(self.renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 74, in draw_wrapper result = draw(artist, renderer, args, kwargs) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/figure.py", line 2845, in draw mimage._draw_list_compositing_images( File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/image.py", line 132, in _draw_list_compositing_images a.draw(renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/mpl/geoaxes.py", line 558, in draw return matplotlib.axes.Axes.draw(self, renderer=renderer, kwargs) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/axes/_base.py", line 3091, in draw mimage._draw_list_compositing_images( File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/image.py", line 132, in _draw_list_compositing_images a.draw(renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/collections.py", line 990, in draw super().draw(renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper return draw(artist, renderer) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/collections.py", line 366, in draw transform, transOffset, offsets, paths = self._prepare_points() File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/collections.py", line 343, in _prepare_points paths = [transform.transform_path_non_affine(path) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/collections.py", line 343, in <listcomp> paths = [transform.transform_path_non_affine(path) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/matplotlib/transforms.py", line 2436, in transform_path_non_affine return self._a.transform_path_non_affine(path) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/mpl/geoaxes.py", line 190, in transform_path_non_affine proj_geom = self.target_projection.project_geometry( File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/crs.py", line 805, in project_geometry return getattr(self, method_name)(geometry, src_crs) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/crs.py", line 948, in _project_polygon p_rings, p_mline = self._project_linear_ring(src_ring, src_crs) File "/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/cartopy/crs.py", line 824, in _project_linear_ring multi_line_string = cartopy.trace.project_linear(linear_ring, File "lib/cartopy/trace.pyx", line 628, in cartopy.trace.project_linear File "lib/cartopy/trace.pyx", line 100, in cartopy.trace.geos_from_shapely TypeError: an integer is required ```

Anything else we need to know?

No response

Environment

/home/andrew/miniconda3/envs/AQUATIC/lib/python3.10/site-packages/_distutils_hack/__init__.py:33: UserWarning: Setuptools is replacing distutils. warnings.warn("Setuptools is replacing distutils.") INSTALLED VERSIONS ------------------ commit: None python: 3.10.5 | packaged by conda-forge | (main, Jun 14 2022, 07:04:59) [GCC 10.3.0] python-bits: 64 OS: Linux OS-release: 5.4.0-122-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: 2022.6.0 pandas: 1.4.3 numpy: 1.23.2 scipy: 1.9.0 netCDF4: 1.6.0 pydap: None h5netcdf: None h5py: None Nio: None zarr: None cftime: 1.6.1 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: None dask: 2022.8.0 distributed: 2022.8.0 matplotlib: 3.5.3 cartopy: 0.20.3 seaborn: 0.11.2 numbagg: None fsspec: 2022.7.1 cupy: None pint: None sparse: None flox: None numpy_groupies: None setuptools: 65.0.2 pip: 22.2.2 conda: None pytest: None IPython: 8.4.0 sphinx: None