Fix interpolation in polar plots when theta values go negative. Thanks Jan Gillis for reporting.

mdboom · mdboom · commit 2479a4f08f74 · 2008-09-18T13:09:01.000Z
svn path=/trunk/matplotlib/; revision=6106
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,6 +1,8 @@
+2008-09-18 Fix polar interpolation to handle negative values of theta - MGD
+
 2008-09-14 Reorganized cbook and mlab methods related to numerical
 	   calculations that have little to do with the goals of those two
-	   modules into a separate module numerical_methods.py 
+	   modules into a separate module numerical_methods.py
 	   Also, added ability to select points and stop point selection
 	   with keyboard in ginput and manual contour labeling code.
 	   Finally, fixed contour labeling bug. - DMK
diff --git a/lib/matplotlib/projections/polar.py b/lib/matplotlib/projections/polar.py
@@ -56,6 +56,8 @@ def transform(self, tr):
 
         def transform_path(self, path):
             vertices = path.vertices
+            t = vertices[:, 0:1]
+            t[t != (npy.pi * 2.0)] %= (npy.pi * 2.0)
             if len(vertices) == 2 and vertices[0, 0] == vertices[1, 0]:
                 return Path(self.transform(vertices), path.codes)
             ipath = path.interpolated(self._resolution)
@@ -168,6 +170,7 @@ def __init__(self, *args, **kwargs):
         """
 
         self._rpad = 0.05
+        self.resolution = kwargs.pop('resolution', self.RESOLUTION)
         Axes.__init__(self, *args, **kwargs)
         self.set_aspect('equal', adjustable='box', anchor='C')
         self.cla()
@@ -195,7 +198,7 @@ def _set_lim_and_transforms(self):
         self.transScale = TransformWrapper(IdentityTransform())
 
         # A (possibly non-linear) projection on the (already scaled) data
-        self.transProjection = self.PolarTransform(self.RESOLUTION)
+        self.transProjection = self.PolarTransform(self.resolution)
 
         # An affine transformation on the data, generally to limit the
         # range of the axes
