bugfix: facetgrid now uses hue_style

Author: dcherian

xarray/plot/dataset_plot.py

@@ -25,8 +25,8 @@ def _infer_scatter_meta_data(ds, x, y, hue, hue_style, add_colorbar,
 
     dims_coords = set(list(ds.coords) + list(ds.dims))
     if hue is not None and hue not in dims_coords:
-        raise ValueError(hue + ' must be either one of ({0:s})'
-                               ''.format(', '.join(dims_coords)))
+        raise ValueError('hue must be one of ({0:s}) but is {hue}'
+                         'instead.'.format(', '.join(dims_coords)), hue)
 
     if hue:
         hue_is_numeric = (_ensure_numeric(ds[hue].values)
@@ -195,7 +195,8 @@ def scatter(ds, x, y, hue=None, hue_style=None, col=None, row=None,
         g = FacetGrid(data=ds, col=col, row=row, col_wrap=col_wrap,
                       sharex=sharex, sharey=sharey, figsize=figsize,
                       aspect=aspect, size=size, subplot_kws=subplot_kws)
-        return g.map_scatter(x=x, y=y, hue=hue, add_colorbar=add_colorbar,
+        return g.map_scatter(x=x, y=y, hue=hue, hue_style=hue_style,
+                             add_colorbar=add_colorbar,
                              add_legend=add_legend, **kwargs)
 
     figsize = kwargs.pop('figsize', None)

xarray/tests/test_plot.py

@@ -1861,6 +1861,16 @@ def test_datetime_hue(self, hue_style):
         ds2['hue'] = pd.timedelta_range('-1D', periods=4, freq='D')
         ds2.plot.scatter(x='A', y='B', hue='hue', hue_style=hue_style)
 
+    @pytest.mark.parametrize('hue_style, map_type',
+                             (['discrete', list],
+                              ['continuous', mpl.collections.PathCollection]))
+    def test_facetgrid_hue_style(self, hue_style, map_type):
+        g = self.ds.plot.scatter(x='A', y='B', row='row', col='col', hue='hue',
+                                 hue_style=hue_style)
+        # for 'discrete' a list is appended to _mappables
+        # for 'continuous', should be single PathCollection
+        assert type(g._mappables[-1]) == map_type
+
     def test_non_numeric_legend(self):
         ds2 = self.ds.copy()
         ds2['hue'] = ['a', 'b', 'c', 'd']