facetgrid: properly support cbar_kwargs. (#2444)

* facetgrid: properly support cbar_kwargs.

* Update doc/plotting.rst

* Update xarray/plot/facetgrid.py

* Update whats-new.rst

Author: dcherian

doc/plotting.rst

@@ -527,7 +527,8 @@ Faceted plotting supports other arguments common to xarray 2d plots.
 
     @savefig plot_facet_robust.png
     g = hasoutliers.plot.pcolormesh('lon', 'lat', col='time', col_wrap=3,
-                                    robust=True, cmap='viridis')
+                                    robust=True, cmap='viridis',
+				     cbar_kwargs={'label': 'this has outliers'})
 
 FacetGrid Objects
 ~~~~~~~~~~~~~~~~~

doc/whats-new.rst

@@ -86,6 +86,9 @@ Enhancements
 Bug fixes
 ~~~~~~~~~
 
+- ``FacetGrid`` now properly uses the ``cbar_kwargs`` keyword argument.
+  (:issue:`1504`, :issue:`1717`)
+  By `Deepak Cherian <https://github.com/dcherian>`_.
 - Addition and subtraction operators used with a CFTimeIndex now preserve the
   index's type. (:issue:`2244`).
   By `Spencer Clark <https://github.com/spencerkclark>`_.

xarray/plot/facetgrid.py

@@ -223,6 +223,11 @@ def map_dataarray(self, func, x, y, **kwargs):
 
         cmapkw = kwargs.get('cmap')
         colorskw = kwargs.get('colors')
+        cbar_kwargs = kwargs.pop('cbar_kwargs', {})
+        cbar_kwargs = {} if cbar_kwargs is None else dict(cbar_kwargs)
+
+        if kwargs.get('cbar_ax', None) is not None:
+            raise ValueError('cbar_ax not supported by FacetGrid.')
 
         # colors is mutually exclusive with cmap
         if cmapkw and colorskw:
@@ -264,7 +269,7 @@ def map_dataarray(self, func, x, y, **kwargs):
         self._finalize_grid(x, y)
 
         if kwargs.get('add_colorbar', True):
-            self.add_colorbar()
+            self.add_colorbar(**cbar_kwargs)
 
         return self
 

xarray/tests/test_plot.py

@@ -1147,6 +1147,23 @@ def test_facetgrid_cmap(self):
         # check that all colormaps are the same
         assert len(set(m.get_cmap().name for m in fg._mappables)) == 1
 
+    def test_facetgrid_cbar_kwargs(self):
+        a = easy_array((10, 15, 2, 3))
+        d = DataArray(a, dims=['y', 'x', 'columns', 'rows'])
+        g = self.plotfunc(d, x='x', y='y', col='columns', row='rows',
+                          cbar_kwargs={'label': 'test_label'})
+
+        # catch contour case
+        if hasattr(g, 'cbar'):
+            assert g.cbar._label == 'test_label'
+
+    def test_facetgrid_no_cbar_ax(self):
+        a = easy_array((10, 15, 2, 3))
+        d = DataArray(a, dims=['y', 'x', 'columns', 'rows'])
+        with pytest.raises(ValueError):
+            g = self.plotfunc(d, x='x', y='y', col='columns', row='rows',
+                              cbar_ax=1)
+
     def test_cmap_and_color_both(self):
         with pytest.raises(ValueError):
             self.plotmethod(colors='k', cmap='RdBu')