matplotlib · efiring · Aug 21, 2017 · Jul 17, 2015 · Jul 14, 2015 · Jul 17, 2015
diff --git a/doc/users/next_whats_new/2015-10-31_polar_limits.rst b/doc/users/next_whats_new/2015-10-31_polar_limits.rst
@@ -0,0 +1,37 @@
+Enhancements to polar plot
+--------------------------
+
+The polar axes transforms have been greatly re-factored to allow for more
+customization of view limits and tick labelling. Additional options for view
+limits allow for creating an annulus, a sector, or some combination of the two.
+
+The :meth:`~matplotlib.axes.projections.polar.PolarAxes.set_rorigin` method may
+be used to provide an offset to the minimum plotting radius, producing an
+annulus.
+
+The :meth:`~matplotlib.projections.polar.PolarAxes.set_theta_zero_location` now
+has an optional :code:`offset` argument. This argument may be used to further
+specify the zero location based on the given anchor point.
+
+.. figure:: ../../gallery/pie_and_polar_charts/images/sphx_glr_polar_scatter_001.png
+   :target: ../../gallery/pie_and_polar_charts/polar_scatter.html
+   :align: center
+   :scale: 50
+
+   Polar Offset Demo
+
+The :meth:`~matplotlib.axes.projections.polar.PolarAxes.set_thetamin` and
+:meth:`~matplotlib.axes.projections.polar.PolarAxes.set_thetamax` methods may
+be used to limit the range of angles plotted, producing sectors of a circle.
+
+.. figure:: ../../gallery/pie_and_polar_charts/images/sphx_glr_polar_scatter_002.png
+   :target: ../../gallery/pie_and_polar_charts/polar_scatter.html
+   :align: center
+   :scale: 50
+
+   Polar Sector Demo
+
+Previous releases allowed plots containing negative radii for which the
+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.
diff --git a/examples/api/radar_chart.py b/examples/api/radar_chart.py
@@ -37,11 +37,10 @@ def radar_factory(num_vars, frame='circle'):
     """
     # calculate evenly-spaced axis angles
     theta = np.linspace(0, 2*np.pi, num_vars, endpoint=False)
-    # rotate theta such that the first axis is at the top
-    theta += np.pi/2
 
     def draw_poly_patch(self):
-        verts = unit_poly_verts(theta)
+        # rotate theta such that the first axis is at the top
+        verts = unit_poly_verts(theta + np.pi / 2)
         return plt.Polygon(verts, closed=True, edgecolor='k')
 
     def draw_circle_patch(self):
@@ -60,6 +59,11 @@ class RadarAxes(PolarAxes):
         # define draw_frame method
         draw_patch = patch_dict[frame]
 
+        def __init__(self, *args, **kwargs):
+            super(RadarAxes, self).__init__(*args, **kwargs)
+            # rotate plot such that the first axis is at the top
+            self.set_theta_zero_location('N')
+
         def fill(self, *args, **kwargs):
             """Override fill so that line is closed by default"""
             closed = kwargs.pop('closed', True)
@@ -93,7 +97,7 @@ def _gen_axes_spines(self):
 
             # spine_type must be 'left', 'right', 'top', 'bottom', or `circle`.
             spine_type = 'circle'
-            verts = unit_poly_verts(theta)
+            verts = unit_poly_verts(theta + np.pi / 2)
             # close off polygon by repeating first vertex
             verts.append(verts[0])
             path = Path(verts)

diff --git a/examples/pie_and_polar_charts/polar_scatter.py b/examples/pie_and_polar_charts/polar_scatter.py
@@ -3,8 +3,6 @@
 Scatter plot on polar axis
 ==========================
 
-Demo of scatter plot on a polar axis.
-
 Size increases radially in this example and color increases with angle
 (just to verify the symbols are being scattered correctly).
 """
@@ -22,7 +20,37 @@
 area = 200 * r**2
 colors = theta
 
-ax = plt.subplot(111, projection='polar')
+fig = plt.figure()
+ax = fig.add_subplot(111, projection='polar')
 c = ax.scatter(theta, r, c=colors, s=area, cmap='hsv', alpha=0.75)
 
+###############################################################################
+# Scatter plot on polar axis, with offset origin
+# ----------------------------------------------
+#
+# The main difference with the previous plot is the configuration of the origin
+# radius, producing an annulus. Additionally, the theta zero location is set to
+# rotate the plot.
+
+fig = plt.figure()
+ax = fig.add_subplot(111, polar=True)
+c = ax.scatter(theta, r, c=colors, s=area, cmap='hsv', alpha=0.75)
+
+ax.set_rorigin(-2.5)
+ax.set_theta_zero_location('W', offset=10)
+
+###############################################################################
+# Scatter plot on polar axis confined to a sector
+# -----------------------------------------------
+#
+# The main difference with the previous plots is the configuration of the
+# theta start and end limits, producing a sector instead of a full circle.
+
+fig = plt.figure()
+ax = fig.add_subplot(111, polar=True)
+c = ax.scatter(theta, r, c=colors, s=area, cmap='hsv', alpha=0.75)
+
+ax.set_thetamin(45)
+ax.set_thetamax(135)
+
 plt.show()