ENH: Plotting for groupby_bins

doc/whats-new.rst

@@ -37,6 +37,9 @@ Documentation
 Enhancements
 ~~~~~~~~~~~~
 
+- DataArrays created with groupby_bins supported by plotting routines. 
+  By `Maximilian Maahn <https://github.com/maahn>`_.
+
 - :py:meth:`~DataArray.cumsum` and :py:meth:`~DataArray.cumprod` now support
   aggregation over multiple dimensions at the same time. This is the default
   behavior when dimensions are not specified (previously this raised an error).

xarray/plot/plot.py

@@ -48,14 +48,23 @@ def _ensure_plottable(*args):
     axis.
     """
     numpy_types = [np.floating, np.integer, np.timedelta64, np.datetime64]
-    other_types = [datetime]
+    other_types = [datetime, pd.Interval]
 
     for x in args:
         if not (_valid_numpy_subdtype(np.array(x), numpy_types) or
                 _valid_other_type(np.array(x), other_types)):
             raise TypeError('Plotting requires coordinates to be numeric '
                             'or dates of type np.datetime64 or '
-                            'datetime.datetime.')
+                            'datetime.datetime or pd.Interval.')
+
+
+def _interval_to_mid_points(array):
+    """
+    Helper function which returns an array
+    with the Intervals' mid points.
+    """
+
+    return np.asarray(list(map(lambda x: x.mid, array)))
 
 
 def _easy_facetgrid(darray, plotfunc, x, y, row=None, col=None,
@@ -267,7 +276,14 @@ def line(darray, *args, **kwargs):
 
     _ensure_plottable(xplt)
 
-    primitive = ax.plot(xplt, yplt, *args, **kwargs)
+    # Remove pd.Intervals if contained in xplt.values.
+    if _valid_other_type(xplt.values, [pd.Interval]):
+        xplt_val = _interval_to_mid_points(xplt.values)
+        xlabel += '_center'
+    else:
+        xplt_val = xplt.values
+
+    primitive = ax.plot(xplt_val, yplt, *args, **kwargs)
 
     if xlabel is not None:
         ax.set_xlabel(xlabel)
@@ -610,6 +626,16 @@ def newplotfunc(darray, x=None, y=None, figsize=None, size=None,
 
         _ensure_plottable(xval, yval)
 
+        # Replace pd.Intervals if contained in xval or yval.
+        if _valid_other_type(xval, [pd.Interval]):
+            xplt = _interval_to_mid_points(xval)
+        else:
+            xplt = xval
+        if _valid_other_type(yval, [pd.Interval]):
+            yplt = _interval_to_mid_points(yval)
+        else:
+            yplt = yval
+
         if 'contour' in plotfunc.__name__ and levels is None:
             levels = 7  # this is the matplotlib default
 
@@ -645,7 +671,7 @@ def newplotfunc(darray, x=None, y=None, figsize=None, size=None,
                              "in xarray")
 
         ax = get_axis(figsize, size, aspect, ax)
-        primitive = plotfunc(xval, yval, zval, ax=ax, cmap=cmap_params['cmap'],
+        primitive = plotfunc(xplt, yplt, zval, ax=ax, cmap=cmap_params['cmap'],
                              vmin=cmap_params['vmin'],
                              vmax=cmap_params['vmax'],
                              **kwargs)
@@ -674,7 +700,7 @@ def newplotfunc(darray, x=None, y=None, figsize=None, size=None,
         _update_axes_limits(ax, xincrease, yincrease)
 
         # Rotate dates on xlabels
-        if np.issubdtype(xval.dtype, np.datetime64):
+        if np.issubdtype(xplt.dtype, np.datetime64):
             ax.get_figure().autofmt_xdate()
 
         return primitive

xarray/tests/test_plot.py

@@ -297,6 +297,19 @@ def test_convenient_facetgrid_4d(self):
         with raises_regex(ValueError, '[Ff]acet'):
             d.plot(x='x', y='y', col='columns', ax=plt.gca())
 
+    def test_coord_with_interval(self):
+        for dim in self.darray.dims:
+            for method in ['argmax', 'argmin', 'max', 'min',
+                           'mean', 'prod', 'sum',
+                           'std', 'var', 'median']:
+                gp = self.darray.groupby_bins(dim, [-1, 0, 1, 2])
+                getattr(gp, method)().plot()
+
+    def test_coord_with_interval_label_contains_center(self):
+        for dim in self.darray.dims:
+            self.darray.groupby_bins(dim, [-1, 0, 1, 2]).mean().plot()
+            assert plt.gca().get_xlabel().endswith('_center')
+
 
 class TestPlot1D(PlotTestCase):
     def setUp(self):
@@ -404,6 +417,14 @@ def test_plot_nans(self):
         self.darray[0, 0, 0] = np.nan
         self.darray.plot.hist()
 
+    def test_hist_coord_with_interval(self):
+        for dim in self.darray.dims:
+            for method in ['argmax', 'argmin', 'max', 'min',
+                           'mean', 'prod', 'sum',
+                           'std', 'var', 'median']:
+                gp = self.darray.groupby_bins(dim, [-1, 0, 1, 2])
+                getattr(gp, method)().plot.hist(range=(-1, 2))
+
 
 @requires_matplotlib
 class TestDetermineCmapParams(TestCase):
@@ -959,6 +980,16 @@ def test_cmap_and_color_both(self):
         with pytest.raises(ValueError):
             self.plotmethod(colors='k', cmap='RdBu')
 
+    def test_2d_coord_with_interval(self):
+        for dim in self.darray.dims:
+            gp = self.darray.groupby_bins(dim, range(15))
+            for method in ['argmax', 'argmin', 'max', 'min',
+                           'mean', 'prod', 'sum',
+                           'std', 'var', 'median']:
+                gp_method = getattr(gp, method)(dim)
+                for kind in ['imshow', 'pcolormesh', 'contourf', 'contour']:
+                    getattr(gp_method.plot, kind)()
+
 
 @pytest.mark.slow
 class TestContourf(Common2dMixin, PlotTestCase):