twinx and twiny inherit autoscale setting for shared axis from parent Axes

naoyak · naoyak · commit ead481759dc3 · 2017-01-26T13:50:24.000-08:00
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -3904,16 +3904,16 @@ def twinx(self):
         """
         Create a twin Axes sharing the xaxis
 
-        Create a twin of Axes for generating a plot with a shared
-        x-axis but independent y-axis.  The y-axis of self will have
-        ticks on left and the returned axes will have ticks on the
-        right. To ensure tick marks of both axis align, see
+        Create a twin Axes instance for generating a plot with a shared
+        x-axis and two independent y-axes on either side (left and right).
+        The x-axis autoscale setting will be inherited from the parent Axes. To
+        ensure tick marks of both axis align, see
         `~matplotlib.ticker.LinearLocator`
 
         Returns
         -------
-        Axis
-            The newly created axis
+        Axes
+            The newly created Axes instance
 
         Notes
         -----
@@ -3924,6 +3924,7 @@ def twinx(self):
         ax2.yaxis.tick_right()
         ax2.yaxis.set_label_position('right')
         ax2.yaxis.set_offset_position('right')
+        ax2.set_autoscalex_on(self.get_autoscalex_on())
         self.yaxis.tick_left()
         ax2.xaxis.set_visible(False)
         ax2.patch.set_visible(False)
@@ -3933,25 +3934,26 @@ def twiny(self):
         """
         Create a twin Axes sharing the yaxis
 
-        Create a twin of Axes for generating a plot with a shared
-        y-axis but independent x-axis.  The x-axis of self will have
-        ticks on bottom and the returned axes will have ticks on the
-        top.
+        Create a twin Axes instance for generating a plot with a shared
+        y-axis and two independent x-axes on either side (top and bottom). The
+        y-axis autoscale setting will be inherited from the parent Axes. To
+        ensure tick marks of both axis align, see
+        `~matplotlib.ticker.LinearLocator`
 
         Returns
         -------
-        Axis
-            The newly created axis
+        Axes
+            The newly created Axes instance
 
         Notes
-        ------
+        -----
         For those who are 'picking' artists while using twiny, pick
         events are only called for the artists in the top-most axes.
         """
-
         ax2 = self._make_twin_axes(sharey=self)
         ax2.xaxis.tick_top()
         ax2.xaxis.set_label_position('top')
+        ax2.set_autoscaley_on(self.get_autoscaley_on())
         self.xaxis.tick_bottom()
         ax2.yaxis.set_visible(False)
         ax2.patch.set_visible(False)
diff --git a/lib/matplotlib/tests/baseline_images/test_axes/twin_autoscale.png b/lib/matplotlib/tests/baseline_images/test_axes/twin_autoscale.png
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -145,6 +145,42 @@ def test_twinx_cla():
     assert ax.yaxis.get_visible()
 
 
+@image_comparison(baseline_images=['twin_autoscale'], extensions=['png'])
+def test_twinx_axis_scales():
+    x = np.array([0, 0.5, 1])
+    y = 0.5 * x
+    x2 = np.array([0, 1, 2])
+    y2 = 2 * x2
+
+    fig = plt.figure()
+    ax = fig.add_axes((0, 0, 1, 1), autoscalex_on=False, autoscaley_on=False)
+    ax.plot(x, y, color='blue', lw=10)
+
+    ax2 = plt.twinx(ax)
+    ax2.plot(x2, y2, 'r--', lw=5)
+
+    ax.margins(0, 0)
+    ax2.margins(0, 0)
+
+
+@cleanup
+def test_twin_inherit_autoscale_setting():
+    fig, ax = plt.subplots()
+    ax_x_on = ax.twinx()
+    ax.set_autoscalex_on(False)
+    ax_x_off = ax.twinx()
+
+    assert ax_x_on.get_autoscalex_on()
+    assert not ax_x_off.get_autoscalex_on()
+
+    ax_y_on = ax.twiny()
+    ax.set_autoscaley_on(False)
+    ax_y_off = ax.twiny()
+
+    assert ax_y_on.get_autoscaley_on()
+    assert not ax_y_off.get_autoscaley_on()
+
+
 @image_comparison(baseline_images=["minorticks_on_rcParams_both"], extensions=['png'])
 def test_minorticks_on_rcParams_both():
     fig = plt.figure()
