FIX: update scale on shared axes

Fixes matplotlib#4450

Or at least the scary part of the scale change not propagating
to all shared axes.

Author: tacaswell

lib/matplotlib/axes/_base.py

@@ -2673,10 +2673,13 @@ def set_xscale(self, value, **kwargs):
         # around zero
         if value.lower() == 'log' and 'nonposx' not in kwargs.keys():
             kwargs['nonposx'] = 'clip'
-        self.xaxis._set_scale(value, **kwargs)
-        self.autoscale_view(scaley=False)
-        self._update_transScale()
-        self.stale = True
+
+        g = self.get_shared_x_axes()
+        for ax in g.get_siblings(self):
+            ax.xaxis._set_scale(value, **kwargs)
+            ax.autoscale_view(scaley=False)
+            ax._update_transScale()
+            ax.stale = True
 
     def get_xticks(self, minor=False):
         """Return the x ticks as a list of locations"""
@@ -2926,10 +2929,13 @@ def set_yscale(self, value, **kwargs):
         # around zero
         if value.lower() == 'log' and 'nonposy' not in kwargs.keys():
             kwargs['nonposy'] = 'clip'
-        self.yaxis._set_scale(value, **kwargs)
-        self.autoscale_view(scalex=False)
-        self._update_transScale()
-        self.stale = True
+
+        g = self.get_shared_y_axes()
+        for ax in g.get_siblings(self):
+            ax.yaxis._set_scale(value, **kwargs)
+            ax.autoscale_view(scalex=False)
+            ax._update_transScale()
+            ax.stale = True
 
     def get_yticks(self, minor=False):
         """Return the y ticks as a list of locations"""

lib/matplotlib/tests/test_axes.py

@@ -3796,8 +3796,9 @@ def test_rc_spines():
     with matplotlib.rc_context(rc_dict):
         fig, ax = plt.subplots()
 
+
 @image_comparison(baseline_images=['rc_grid'], extensions=['png'],
-                  savefig_kwarg={'dpi':40})
+                  savefig_kwarg={'dpi': 40})
 def test_rc_grid():
     fig = plt.figure()
     rc_dict0 = {
@@ -3811,11 +3812,13 @@ def test_rc_grid():
     }
     dict_list = [rc_dict0, rc_dict1, rc_dict2]
 
-    i=1
+    i = 1
     for rc_dict in dict_list:
         with matplotlib.rc_context(rc_dict):
             fig.add_subplot(3, 1, i)
             i += 1
+
+
 @cleanup
 def test_bar_negative_width():
     fig, ax = plt.subplots()
@@ -3826,6 +3829,7 @@ def test_bar_negative_width():
         assert_equal(b._width, 1)
         assert_equal(b._height, indx + 1)
 
+
 @cleanup
 def test_square_plot():
     x = np.arange(4)
@@ -3837,6 +3841,7 @@ def test_square_plot():
     assert_true(np.diff(xlim) == np.diff(ylim))
     assert_true(ax.get_aspect() == 'equal')
 
+
 @cleanup
 def test_no_None():
     fig, ax = plt.subplots()
@@ -3855,6 +3860,24 @@ def test_pcolor_fast_non_uniform():
     ax.pcolorfast(X, Y, Z.T)
 
 
+@cleanup
+def test_shared_scale():
+    fig, axs = plt.subplots(2, 2, sharex=True, sharey=True)
+
+    axs[0, 0].set_xscale("log")
+    axs[0, 0].set_yscale("log")
+
+    for ax in axs.flat:
+        assert_equal(ax.get_yscale(), 'log')
+        assert_equal(ax.get_xscale(), 'log')
+
+    axs[1, 1].set_xscale("linear")
+    axs[1, 1].set_yscale("linear")
+
+    for ax in axs.flat:
+        assert_equal(ax.get_yscale(), 'linear')
+        assert_equal(ax.get_xscale(), 'linear')
+
 if __name__ == '__main__':
     import nose
     import sys