Remove extra stickies in barstacked histogram.

anntzer · anntzer · commit 2b5b5a91f6c0 · 2020-09-12T16:18:34.000+02:00
If we let stacked bars add their sticky edges in the middle of the bars,
margin expansion can later bump into these barriers.
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -6660,13 +6660,19 @@ def hist(self, x, bins=None, range=None, density=False, weights=None,
                     height = m - bottom
                 else:
                     height = m
-                patch = _barfunc(bins[:-1]+boffset, height, width,
-                                 align='center', log=log,
-                                 color=c, **{bottom_kwarg: bottom})
-                patches.append(patch)
+                bars = _barfunc(bins[:-1]+boffset, height, width,
+                                align='center', log=log,
+                                color=c, **{bottom_kwarg: bottom})
+                patches.append(bars)
                 if stacked:
                     bottom[:] = m
                 boffset += dw
+            # Remove stickies from all bars but the lowest ones, as otherwise
+            # margin expansion would be unable to cross the stickies in the
+            # middle of the bars.
+            for bars in patches[1:]:
+                for patch in bars:
+                    patch.sticky_edges.x[:] = patch.sticky_edges.y[:] = []
 
         elif histtype.startswith('step'):
             # these define the perimeter of the polygon
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -1679,6 +1679,16 @@ def test_hist_log_2(fig_test, fig_ref):
             ax.hist(1, 1, log=True, histtype=histtype)
 
 
+def test_hist_log_barstacked():
+    fig, axs = plt.subplots(2)
+    axs[0].hist([[0], [0, 1]], 2, histtype="barstacked")
+    axs[0].set_yscale("log")
+    axs[1].hist([0, 0, 1], 2, histtype="barstacked")
+    axs[1].set_yscale("log")
+    fig.canvas.draw()
+    assert axs[0].get_ylim() == axs[1].get_ylim()
+
+
 @image_comparison(['hist_bar_empty.png'], remove_text=True)
 def test_hist_bar_empty():
     # From #3886: creating hist from empty dataset raises ValueError
