Fix label_outer in the presence of colorbars.

anntzer · anntzer · commit add6bbf3d76d · 2025-05-28T13:34:34.000+02:00
The subgridspec to be considered should be the one containing both the
axes and the colorbar, not the sub-subgridspec of just the axes.
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -4749,14 +4749,39 @@ def label_outer(self, remove_inner_ticks=False):
         self._label_outer_yaxis(skip_non_rectangular_axes=False,
                                 remove_inner_ticks=remove_inner_ticks)
 
+    def _get_subplotspec_with_optional_colorbar(self):
+        """
+        Return the subplotspec for this Axes, except that if this Axes has been
+        moved to a subgridspec to make room for a colorbar, then return the
+        subplotspec that encloses both this Axes and the colorbar Axes.
+        """
+        ss = self.get_subplotspec()
+        if not ss:
+            return
+        gs = ss.get_gridspec()
+        # Match against subgridspec hierarchy set up by colorbar.make_axes_gridspec.
+        if (isinstance(gs, mpl.gridspec.GridSpecFromSubplotSpec)
+                and gs.nrows * gs.ncols == 6):
+            for ax in self.figure.axes:
+                if (ax is not self
+                        and hasattr(ax, "_colorbar_info")
+                        and ax.get_subplotspec()
+                        and isinstance(ax.get_subplotspec().get_gridspec(),
+                                       mpl.gridspec.GridSpecFromSubplotSpec)
+                        and (ax.get_subplotspec().get_gridspec()._subplot_spec
+                             is gs._subplot_spec)):
+                    ss = gs._subplot_spec
+                    break
+        return ss
+
     def _label_outer_xaxis(self, *, skip_non_rectangular_axes,
                            remove_inner_ticks=False):
         # see documentation in label_outer.
         if skip_non_rectangular_axes and not isinstance(self.patch,
                                                         mpl.patches.Rectangle):
             return
-        ss = self.get_subplotspec()
-        if not ss:
+        ss = self._get_subplotspec_with_optional_colorbar()
+        if ss is None:
             return
         label_position = self.xaxis.get_label_position()
         if not ss.is_first_row():  # Remove top label/ticklabels/offsettext.
@@ -4782,8 +4807,8 @@ def _label_outer_yaxis(self, *, skip_non_rectangular_axes,
         if skip_non_rectangular_axes and not isinstance(self.patch,
                                                         mpl.patches.Rectangle):
             return
-        ss = self.get_subplotspec()
-        if not ss:
+        ss = self._get_subplotspec_with_optional_colorbar()
+        if ss is None:
             return
         label_position = self.yaxis.get_label_position()
         if not ss.is_first_col():  # Remove left label/ticklabels/offsettext.
diff --git a/lib/matplotlib/tests/test_subplots.py b/lib/matplotlib/tests/test_subplots.py
@@ -4,6 +4,7 @@
 import numpy as np
 import pytest
 
+import matplotlib as mpl
 from matplotlib.axes import Axes, SubplotBase
 import matplotlib.pyplot as plt
 from matplotlib.testing.decorators import check_figures_equal, image_comparison
@@ -111,10 +112,15 @@ def test_shared():
 
 
 @pytest.mark.parametrize('remove_ticks', [True, False])
-def test_label_outer(remove_ticks):
-    f, axs = plt.subplots(2, 2, sharex=True, sharey=True)
+@pytest.mark.parametrize('layout_engine', ['tight', 'constrained'])
+@pytest.mark.parametrize('with_colorbar', [True, False])
+def test_label_outer(remove_ticks, layout_engine, with_colorbar):
+    fig = plt.figure(layout=layout_engine)
+    axs = fig.subplots(2, 2, sharex=True, sharey=True)
     for ax in axs.flat:
         ax.set(xlabel="foo", ylabel="bar")
+        if with_colorbar:
+            fig.colorbar(mpl.cm.ScalarMappable(), ax=ax)
         ax.label_outer(remove_inner_ticks=remove_ticks)
     check_ticklabel_visible(
         axs.flat, [False, False, True, True], [True, False, True, False])
