Merge pull request matplotlib#9068 from QuLogic/polar-ticks

ENH: Polar tick improvements

Author: tacaswell

doc/users/whats_new.rst

@@ -62,6 +62,12 @@ negative values are simply used as labels, and the real radius is shifted by
 the configured minimum. This release also allows negative radii to be used for
 grids and ticks, which were previously silently ignored.
 
+Radial ticks have been modified to be parallel to the circular grid line, and
+angular ticks have been modified to be parallel to the grid line. It may also
+be useful to rotate tick *labels* to match the boundary. Calling
+``ax.tick_params(rotation='auto')`` will enable new behavior: radial tick
+labels will be parallel to the circular grid line, and angular tick labels will
+be perpendicular to the grid line (i.e., parallel to the outer boundary.)
 
 
 Merge JSAnimation

lib/matplotlib/axis.py

@@ -140,7 +140,7 @@ def __init__(self, axes, loc, label,
             labelsize = rcParams['%s.labelsize' % name]
         self._labelsize = labelsize
 
-        self._labelrotation = labelrotation
+        self._set_labelrotation(labelrotation)
 
         if zorder is None:
             if major:
@@ -167,6 +167,20 @@ def __init__(self, axes, loc, label,
 
         self.update_position(loc)
 
+    def _set_labelrotation(self, labelrotation):
+        if isinstance(labelrotation, six.string_types):
+            mode = labelrotation
+            angle = 0
+        elif isinstance(labelrotation, (tuple, list)):
+            mode, angle = labelrotation
+        else:
+            mode = 'default'
+            angle = labelrotation
+        if mode not in ('auto', 'default'):
+            raise ValueError("Label rotation mode must be 'default' or "
+                             "'auto', not '{}'.".format(mode))
+        self._labelrotation = (mode, angle)
+
     def apply_tickdir(self, tickdir):
         """
         Calculate self._pad and self._tickmarkers
@@ -331,8 +345,14 @@ def _apply_params(self, **kw):
             self.tick2line.set(**tick_kw)
             for k, v in six.iteritems(tick_kw):
                 setattr(self, '_' + k, v)
+
+        if 'labelrotation' in kw:
+            self._set_labelrotation(kw.pop('labelrotation'))
+            self.label1.set(rotation=self._labelrotation[1])
+            self.label2.set(rotation=self._labelrotation[1])
+
         label_list = [k for k in six.iteritems(kw)
-                      if k[0] in ['labelsize', 'labelcolor', 'labelrotation']]
+                      if k[0] in ['labelsize', 'labelcolor']]
         if label_list:
             label_kw = {k[5:]: v for k, v in label_list}
             self.label1.set(**label_kw)