Fix step plots with hue

doc/whats-new.rst

@@ -53,6 +53,8 @@ Bug fixes
   By `Michael Niklas <https://github.com/headtr1ck>`_.
 - Harmonize returned multi-indexed indexes when applying ``concat`` along new dimension (:issue:`6881`, :pull:`6889`)
   By `Fabian Hofmann <https://github.com/FabianHofmann>`_.
+- Fix step plots with ``hue`` arg. (:pull:`6944`)
+  By `András Gunyhó <https://github.com/mgunyho>`_.
 
 Documentation
 ~~~~~~~~~~~~~

xarray/plot/utils.py

@@ -564,13 +564,16 @@ def _resolve_intervals_1dplot(
     if kwargs.get("drawstyle", "").startswith("steps-"):
 
         remove_drawstyle = False
+
         # Convert intervals to double points
-        if _valid_other_type(np.array([xval, yval]), [pd.Interval]):
+        x_is_interval = _valid_other_type(xval, [pd.Interval])
+        y_is_interval = _valid_other_type(yval, [pd.Interval])
+        if x_is_interval and y_is_interval:
             raise TypeError("Can't step plot intervals against intervals.")
-        if _valid_other_type(xval, [pd.Interval]):
+        elif x_is_interval:
             xval, yval = _interval_to_double_bound_points(xval, yval)
             remove_drawstyle = True
-        if _valid_other_type(yval, [pd.Interval]):
+        elif y_is_interval:
             yval, xval = _interval_to_double_bound_points(yval, xval)
             remove_drawstyle = True
 

xarray/tests/test_plot.py

@@ -796,6 +796,24 @@ def test_step_with_where(self, where):
         hdl = self.darray[0, 0].plot.step(where=where)
         assert hdl[0].get_drawstyle() == f"steps-{where}"
 
+    def test_step_with_hue(self):
+        hdl = self.darray[0].plot.step(hue="dim_2")
+        assert hdl[0].get_drawstyle() == "steps-pre"
+
+    @pytest.mark.parametrize("where", ["pre", "post", "mid"])
+    def test_step_with_hue_and_where(self, where):
+        hdl = self.darray[0].plot.step(hue="dim_2", where=where)
+        assert hdl[0].get_drawstyle() == f"steps-{where}"
+
+    def test_drawstyle_steps(self):
+        hdl = self.darray[0].plot(hue="dim_2", drawstyle="steps")
+        assert hdl[0].get_drawstyle() == "steps"
+
+    @pytest.mark.parametrize("where", ["pre", "post", "mid"])
+    def test_drawstyle_steps_with_where(self, where):
+        hdl = self.darray[0].plot(hue="dim_2", drawstyle=f"steps-{where}")
+        assert hdl[0].get_drawstyle() == f"steps-{where}"
+
     def test_coord_with_interval_step(self):
         """Test step plot with intervals."""
         bins = [-1, 0, 1, 2]
@@ -814,6 +832,15 @@ def test_coord_with_interval_step_y(self):
         self.darray.groupby_bins("dim_0", bins).mean(...).plot.step(y="dim_0_bins")
         assert len(plt.gca().lines[0].get_xdata()) == ((len(bins) - 1) * 2)
 
+    def test_coord_with_interval_step_x_and_y_raises_valueeerror(self):
+        """Test that step plot with intervals both on x and y axes raises an error."""
+        arr = xr.DataArray(
+            [pd.Interval(0, 1), pd.Interval(1, 2)],
+            coords=[("x", [pd.Interval(0, 1), pd.Interval(1, 2)])],
+        )
+        with pytest.raises(TypeError, match="intervals against intervals"):
+            arr.plot.step()
+
 
 class TestPlotHistogram(PlotTestCase):
     @pytest.fixture(autouse=True)