Support Xarray Plotting Routines (#760)

* add support for calling xarray's plotting routines

* add tests

* reset mpl backend

* add matplotlib-inline to enviroments

* fix package name

* generalize implementation

ci/asv.yml

@@ -9,6 +9,7 @@ dependencies:
   - gmpy2
   - holoviews
   - matplotlib-base
+  - matplotlib-inline
   - netcdf4
   - numba
   - numpy

ci/docs.yml

@@ -24,6 +24,7 @@ dependencies:
     - sphinx-design
     - nbsphinx
     - matplotlib-base
+    - matplotlib-inline
     - shapely
     - hvplot
     - holoviews

ci/environment.yml

@@ -8,6 +8,7 @@ dependencies:
   - gmpy2
   - holoviews
   - matplotlib-base
+  - matplotlib-inline
   - netcdf4
   - numba
   - numpy

test/test_plot.py

@@ -91,3 +91,24 @@ def test_clabel(self):
         raster_no_clabel = uxds['v1'][0][0].plot.rasterize(method='point')
 
         raster_with_clabel = uxds['v1'][0][0].plot.rasterize(method='point', clabel='Foo')
+
+
+
+class TestXarrayMethods(TestCase):
+
+    def test_dataset(self):
+        """Tests whether a Xarray DataArray method can be called through the
+        UxDataArray plotting accessor."""
+        uxds = ux.open_dataset(gridfile_geoflow, datafile_geoflow)
+
+        # plot.hist() is an xarray method
+        assert hasattr(uxds['v1'].plot, 'hist')
+
+
+    def test_dataarray(self):
+        """Tests whether a Xarray Dataset method can be called through the
+        UxDataset plotting accessor."""
+        uxds = ux.open_dataset(gridfile_geoflow, datafile_geoflow)
+
+        # plot.scatter() is an xarray method
+        assert hasattr(uxds.plot, 'scatter')

uxarray/plot/accessor.py

@@ -3,7 +3,6 @@
 
 import functools
 
-import warnings
 
 if TYPE_CHECKING:
     from uxarray.core.dataset import UxDataset
@@ -12,6 +11,7 @@
 
 import uxarray.plot.grid_plot as grid_plot
 import uxarray.plot.dataarray_plot as dataarray_plot
+import uxarray.plot.utils
 
 import cartopy.crs as ccrs
 
@@ -269,6 +269,22 @@ def __init__(self, uxda: UxDataArray) -> None:
     def __call__(self, **kwargs) -> Any:
         return dataarray_plot.plot(self._uxda, **kwargs)
 
+    def __getattr__(self, name: str) -> Any:
+        """When a function that isn't part of the class is invoked (i.e.
+        uxda.plot.hist), an attempt is made to try and call Xarray's
+        implementation of that function if it exsists."""
+
+        # reference to xr.DataArray.plot accessor
+        xarray_plot_accessor = super(type(self._uxda), self._uxda).plot
+
+        if hasattr(xarray_plot_accessor, name):
+            # call xarray plot method if it exists
+            # use inline backend to reset configuration if holoviz methods were called before
+            uxarray.plot.utils.backend.reset_mpl_backend()
+            return getattr(xarray_plot_accessor, name)
+        else:
+            raise AttributeError(f"Unsupported Plotting Method: '{name}'")
+
     @functools.wraps(dataarray_plot.datashade)
     def datashade(
         self,
@@ -468,7 +484,24 @@ def __init__(self, uxds: UxDataset) -> None:
         self._uxds = uxds
 
     def __call__(self, **kwargs) -> Any:
-        warnings.warn(
-            "Plotting for UxDataset instances not yet supported. Did you mean to plot a data variable, i.e. uxds['data_variable'].plot()"
+        raise ValueError(
+            "UxDataset.plot cannot be called directly. Use an explicit plot method, "
+            "e.g uxds.plot.scatter(...)"
         )
-        pass
+
+    def __getattr__(self, name: str) -> Any:
+        """When a function that isn't part of the class is invoked (i.e.
+        uxds.plot.scatter), an attempt is made to try and call Xarray's
+        implementation of that function if it exists."""
+
+        # reference to xr.Dataset.plot accessor
+        xarray_plot_accessor = super(type(self._uxds), self._uxds).plot
+
+        if hasattr(xarray_plot_accessor, name):
+            # call xarray plot method if it exists
+            # # use inline backend to reset configuration if holoviz methods were called before
+            uxarray.plot.utils.backend.reset_mpl_backend()
+
+            return getattr(xarray_plot_accessor, name)
+        else:
+            raise AttributeError(f"Unsupported Plotting Method: '{name}'")

uxarray/plot/utils.py

@@ -1,4 +1,5 @@
 import holoviews as hv
+import matplotlib as mpl
 
 
 class HoloviewsBackend:
@@ -7,6 +8,7 @@ class HoloviewsBackend:
 
     def __init__(self):
         self.backend = None
+        self.matplotlib_backend = mpl.get_backend()
 
     def assign(self, backend: str):
         """Assigns a backend for use with HoloViews visualization.
@@ -27,6 +29,10 @@ def assign(self, backend: str):
             hv.extension(backend)
             self.backend = backend
 
+    def reset_mpl_backend(self):
+        """Resets the default backend for the ``matplotlib`` module."""
+        mpl.use(self.matplotlib_backend)
+
 
 # global reference to holoviews backend utility class
 backend = HoloviewsBackend()