Merge pull request matplotlib#16717 from CSCD01-team13/bugfix-for-issue-16501

Bugfix for issue 16501 raised ValueError polar subplot with (thetamax - thetamin) > 2pi

Author: dstansby

lib/matplotlib/projections/polar.py

@@ -1040,13 +1040,30 @@ def set_thetalim(self, *args, **kwargs):
         where minval and maxval are the minimum and maximum limits. Values are
         wrapped in to the range :math:`[0, 2\pi]` (in radians), so for example
         it is possible to do ``set_thetalim(-np.pi / 2, np.pi / 2)`` to have
-        an axes symmetric around 0.
+        an axes symmetric around 0. A ValueError is raised if the absolute
+        angle difference is larger than :math:`2\pi`.
         """
+        thetamin = None
+        thetamax = None
+        left = None
+        right = None
+
+        if len(args) == 2:
+            if args[0] is not None and args[1] is not None:
+                left, right = args
+                if abs(right - left) > 2 * np.pi:
+                    raise ValueError('The angle range must be <= 2 pi')
+
         if 'thetamin' in kwargs:
-            kwargs['xmin'] = np.deg2rad(kwargs.pop('thetamin'))
+            thetamin = np.deg2rad(kwargs.pop('thetamin'))
         if 'thetamax' in kwargs:
-            kwargs['xmax'] = np.deg2rad(kwargs.pop('thetamax'))
-        return tuple(np.rad2deg(self.set_xlim(*args, **kwargs)))
+            thetamax = np.deg2rad(kwargs.pop('thetamax'))
+
+        if thetamin is not None and thetamax is not None:
+            if abs(thetamax - thetamin) > 2 * np.pi:
+                raise ValueError('The angle range must be<= 360 degrees')
+        return tuple(np.rad2deg(self.set_xlim(left=left, right=right,
+                                              xmin=thetamin, xmax=thetamax)))
 
     def set_theta_offset(self, offset):
         """

lib/matplotlib/tests/test_subplots.py

@@ -173,3 +173,26 @@ def test_dont_mutate_kwargs():
                            gridspec_kw=gridspec_kw)
     assert subplot_kw == {'sharex': 'all'}
     assert gridspec_kw == {'width_ratios': [1, 2]}
+
+
+def test_subplot_theta_min_max_raise():
+    with pytest.raises(ValueError, match='The angle range ' +
+                                         'must be<= 360 degrees'):
+        ax = plt.subplot(111, projection='polar')
+        ax.set_thetalim(thetamin=800, thetamax=400)
+
+
+def test_subplot_theta_min_max_non_raise():
+    ax = plt.subplot(111, projection='polar')
+    ax.set_thetalim(thetamin=800, thetamax=440)
+
+
+def test_subplot_theta_range_raise():
+    with pytest.raises(ValueError, match='The angle range must be <= 2 pi'):
+        ax = plt.subplot(111, projection='polar')
+        ax.set_thetalim(0, 3 * numpy.pi)
+
+
+def test_subplot_theta_range_normal_non_raise():
+    ax = plt.subplot(111, projection='polar')
+    ax.set_thetalim(0, 2 * numpy.pi)