Raise NotImplementedError when setting aspect on 3D axes

dstansby · dstansby · commit 29b048f5105b · 2019-02-20T20:30:04.000Z
diff --git a/doc/api/next_api_changes/2019-02-20-DS.rst b/doc/api/next_api_changes/2019-02-20-DS.rst
@@ -0,0 +1,7 @@
+Equal aspect axes for 3D plots disabled
+```````````````````````````````````````
+
+Setting the aspect on 3D axes previously returned non-sensical
+results (e.g. see https://github.com/matplotlib/matplotlib/issues/1077).
+Calling ``ax.set_aspect('equal')`` or ``ax.set_aspect(num)``
+on a 3D axes now raises a ``NotImplementedError``.
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -1271,11 +1271,18 @@ def set_aspect(self, aspect, adjustable=None, anchor=None, share=False):
         if not (cbook._str_equal(aspect, 'equal')
                 or cbook._str_equal(aspect, 'auto')):
             aspect = float(aspect)  # raise ValueError if necessary
+
+        if (not cbook._str_equal(aspect, 'auto')) and self.name == '3d':
+            raise NotImplementedError(
+                'It is not currently possible to manually set the aspect '
+                'on 3D axes')
+
         if share:
             axes = set(self._shared_x_axes.get_siblings(self)
                        + self._shared_y_axes.get_siblings(self))
         else:
             axes = [self]
+
         for ax in axes:
             ax._aspect = aspect
 
diff --git a/lib/mpl_toolkits/tests/test_mplot3d.py b/lib/mpl_toolkits/tests/test_mplot3d.py
@@ -11,6 +11,13 @@
 import numpy as np
 
 
+def test_aspect_equal_error():
+    fig = plt.figure()
+    ax = fig.add_subplot(111, projection='3d')
+    with pytest.raises(NotImplementedError):
+        ax.set_aspect('equal')
+
+
 @image_comparison(baseline_images=['bar3d'], remove_text=True)
 def test_bar3d():
     fig = plt.figure()
