examples/xarray_multidimensional_coords.ipynb broken?

[cdeil]

I tried running examples/xarray_multidimensional_coords.ipynb and found a few issues.

First xarray.version didn't exist, so I changed to xr.__version_.

Next I changed to ds = xr.tutorial.open_dataset('rasm').load() to get rid of a deprecation warning.

Finally, the plot example failed like this:

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-23-b7284116c837> in <module>
      2 ax = plt.axes(projection=ccrs.PlateCarree())
      3 ax.set_global()
----> 4 ds.Tair[0].plot.pcolormesh(ax=ax, transform=ccrs.PlateCarree(), x='xc', y='yc', add_colorbar=False)
      5 ax.coastlines()
      6 ax.set_ylim([0,90]);

~/software/anaconda3/envs/multinorm/lib/python3.7/site-packages/xarray/plot/plot.py in plotmethod(_PlotMethods_obj, x, y, figsize, size, aspect, ax, row, col, col_wrap, xincrease, yincrease, add_colorbar, add_labels, vmin, vmax, cmap, colors, center, robust, extend, levels, infer_intervals, subplot_kws, cbar_ax, cbar_kwargs, xscale, yscale, xticks, yticks, xlim, ylim, norm, **kwargs)
    917         for arg in ['_PlotMethods_obj', 'newplotfunc', 'kwargs']:
    918             del allargs[arg]
--> 919         return newplotfunc(**allargs)
    920 
    921     # Add to class _PlotMethods

~/software/anaconda3/envs/multinorm/lib/python3.7/site-packages/xarray/plot/plot.py in 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)
    854                              vmax=cmap_params['vmax'],
    855                              norm=cmap_params['norm'],
--> 856                              **kwargs)
    857 
    858         # Label the plot with metadata

~/software/anaconda3/envs/multinorm/lib/python3.7/site-packages/xarray/plot/plot.py in pcolormesh(x, y, z, ax, infer_intervals, **kwargs)
   1108             y = _infer_interval_breaks(y, axis=0)
   1109 
-> 1110     primitive = ax.pcolormesh(x, y, z, **kwargs)
   1111 
   1112     # by default, pcolormesh picks "round" values for bounds

~/software/anaconda3/envs/multinorm/lib/python3.7/site-packages/cartopy/mpl/geoaxes.py in pcolormesh(self, *args, **kwargs)
   1449                              ' consider using PlateCarree/RotatedPole.')
   1450         kwargs.setdefault('transform', t)
-> 1451         result = self._pcolormesh_patched(*args, **kwargs)
   1452         self.autoscale_view()
   1453         return result

~/software/anaconda3/envs/multinorm/lib/python3.7/site-packages/cartopy/mpl/geoaxes.py in _pcolormesh_patched(self, *args, **kwargs)
   1467         import matplotlib.collections as mcoll
   1468 
-> 1469         if not self._hold:
   1470             self.cla()
   1471 

AttributeError: 'GeoAxesSubplot' object has no attribute '_hold'

It seems examples/xarray_multidimensional_coords.ipynb is broken?
Maybe you could add a CI build to make sure it executes OK?

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None

xarray: 0.11.0
pandas: 0.23.4
numpy: 1.15.4
scipy: 1.1.0
netCDF4: 1.4.2
h5netcdf: None
h5py: None
Nio: None
zarr: None
cftime: 1.0.2.1
PseudonetCDF: None
rasterio: None
iris: None
bottleneck: 1.2.1
cyordereddict: None
dask: 0.20.2
distributed: 1.24.2
matplotlib: 3.0.0
cartopy: 0.16.0
seaborn: None
setuptools: 40.4.3
pip: 18.1
conda: None
pytest: 3.8.2
IPython: 7.0.1
sphinx: 1.8.1

[rabernat]

This error is a matplotlib / cartopy compatibility issue. It can be fixed by upgrading matplotlib to version 3.0.2 (latest release) or upgrading cartopy to 0.17.0, or both.

[cdeil]

But the xr.version.version from cell 1 gives an error on master and the latest release, the notebook won't run as-is, no?

[dcherian]

Thanks @cdeil See #2581

[cdeil]

@dcherian - Thank you!