FIX: tickspacing for subfigures [skip circle]

jklymak · jklymak · commit ebe6d090fa3c · 2021-07-30T07:22:29.000-07:00
diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
@@ -2253,7 +2253,8 @@ def set_default_intervals(self):
 
     def get_tick_space(self):
         ends = self.axes.transAxes.transform([[0, 0], [1, 0]])
-        length = ((ends[1][0] - ends[0][0]) / self.axes.figure.dpi) * 72
+        ends = self.figure.dpi_scale_trans.inverted().transform(ends)
+        length = (ends[1][0] - ends[0][0]) * 72
         # There is a heuristic here that the aspect ratio of tick text
         # is no more than 3:1
         size = self._get_tick_label_size('x') * 3
@@ -2513,7 +2514,8 @@ def set_default_intervals(self):
 
     def get_tick_space(self):
         ends = self.axes.transAxes.transform([[0, 0], [0, 1]])
-        length = ((ends[1][1] - ends[0][1]) / self.axes.figure.dpi) * 72
+        ends = self.figure.dpi_scale_trans.inverted().transform(ends)
+        length = (ends[1][1] - ends[0][1]) * 72
         # Having a spacing of at least 2 just looks good.
         size = self._get_tick_label_size('y') * 2
         if size > 0:
diff --git a/lib/matplotlib/tests/test_figure.py b/lib/matplotlib/tests/test_figure.py
@@ -1031,6 +1031,34 @@ def test_subfigure_spanning():
     np.testing.assert_allclose(sub_figs[2].bbox.max, [w, h / 3])
 
 
+@mpl.style.context('mpl20')
+def test_subfigure_ticks():
+    # This tests a tick-spacing error that only seems applicable
+    # when the subfigures are saved to file.  Its very hard to replicate
+    fig = plt.figure(constrained_layout=True, figsize=(10, 3))
+    # create left/right subfigs nested in bottom subfig
+    (subfig_bl, subfig_br) = fig.subfigures(1, 2, wspace=0.01,
+                                            width_ratios=[7, 2])
+
+    # put ax1-ax3 in gridspec of bottom-left subfig
+    gs = subfig_bl.add_gridspec(nrows=1, ncols=14)
+
+    ax1 = subfig_bl.add_subplot(gs[0, :1])
+    ax1.scatter(x=[-56.46881504821776, 24.179891162109396], y=[1500, 3600])
+
+    ax2 = subfig_bl.add_subplot(gs[0, 1:3], sharey=ax1)
+    ax2.scatter(x=[-126.5357270050049, 94.68456736755368], y=[1500, 3600])
+    ax3 = subfig_bl.add_subplot(gs[0, 3:14], sharey=ax1)
+
+    fig.set_dpi(120)
+    fig.draw_no_output()
+    ticks120 = ax2.get_xticks()
+    fig.set_dpi(300)
+    fig.draw_no_output()
+    ticks300 = ax2.get_xticks()
+    np.testing.assert_allclose(ticks120, ticks300)
+
+
 def test_add_subplot_kwargs():
     # fig.add_subplot() always creates new axes, even if axes kwargs differ.
     fig = plt.figure()
