Use ordered dict for polar spines.

QuLogic · QuLogic · commit 734da0fb33b7 · 2017-08-15T23:10:33.000-04:00
It's not generally necessary on Cartesian plots, but can be troublesome
with wedge-like polar plots where the spines can overlap at acute angles.
diff --git a/lib/matplotlib/projections/polar.py b/lib/matplotlib/projections/polar.py
@@ -1,6 +1,8 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
+import collections
+
 import numpy as np
 
 from matplotlib.axes import Axes
@@ -644,14 +646,14 @@ def _gen_axes_patch(self):
         return mpatches.Wedge((0.5, 0.5), 0.5, 0.0, 360.0)
 
     def _gen_axes_spines(self):
-        spines = {'polar': mspines.Spine.arc_spine(self, 'top',
-                                                   (0.5, 0.5), 0.5,
-                                                   0.0, 360.0),
-                  'start': mspines.Spine.linear_spine(self, 'left'),
-                  'end': mspines.Spine.linear_spine(self, 'right'),
-                  'inner': mspines.Spine.arc_spine(self, 'bottom',
-                                                   (0.5, 0.5), 0.0,
-                                                   0.0, 360.0)}
+        spines = collections.OrderedDict([
+            ('polar', mspines.Spine.arc_spine(self, 'top',
+                                              (0.5, 0.5), 0.5, 0.0, 360.0)),
+            ('start', mspines.Spine.linear_spine(self, 'left')),
+            ('end', mspines.Spine.linear_spine(self, 'right')),
+            ('inner', mspines.Spine.arc_spine(self, 'bottom',
+                                              (0.5, 0.5), 0.0, 0.0, 360.0))
+        ])
         spines['polar'].set_transform(self.transWedge + self.transAxes)
         spines['inner'].set_transform(self.transWedge + self.transAxes)
         spines['start'].set_transform(self._yaxis_transform)
