Fix 1D quiver when transforming projections

lib/cartopy/mpl/geoaxes.py

@@ -1364,7 +1364,7 @@ def pcolor(self, *args, **kwargs):
 
     def quiver(self, x, y, u, v, *args, **kwargs):
         """
-        Plot a 2-D field of arrows.
+        Plot a field of arrows.
 
         Extra Kwargs:
 
@@ -1428,7 +1428,7 @@ def quiver(self, x, y, u, v, *args, **kwargs):
         elif t != self.projection:
             # Transform the vectors if the projection is not the same as the
             # data transform.
-            if x.ndim == 1 and y.ndim == 1:
+            if (x.ndim == 1 and y.ndim == 1) and (x.shape != u.shape):
                 x, y = np.meshgrid(x, y)
             u, v = self.projection.transform_vectors(t, x, y, u, v)
         return matplotlib.axes.Axes.quiver(self, x, y, u, v, *args, **kwargs)

lib/cartopy/tests/test_quiver_shape.py

@@ -0,0 +1,63 @@
+# (C) British Crown Copyright 2015, Met Office
+#
+# This file is part of cartopy.
+#
+# cartopy is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Lesser General Public License as published by the
+# Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# cartopy is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with cartopy.  If not, see <http://www.gnu.org/licenses/>.
+
+from __future__ import (absolute_import, division, print_function)
+
+from nose.tools import raises
+
+import numpy as np
+import matplotlib.pyplot as plt
+
+import cartopy.crs as ccrs
+
+
+class TestQuiverShapes(object):
+
+    @classmethod
+    def setup_class(cls):
+        cls.x = np.arange(-60, 42.5, 2.5)
+        cls.y = np.arange(30, 72.5, 2.5)
+        cls.x2d, cls.y2d = np.meshgrid(cls.x, cls.y)
+        cls.u = np.cos(np.deg2rad(cls.y2d))
+        cls.v = np.cos(2. * np.deg2rad(cls.x2d))
+        cls.rp = ccrs.RotatedPole(pole_longitude=177.5, pole_latitude=37.5)
+        cls.pc = ccrs.PlateCarree()
+
+    def test_quiver_transform_xyuv_1d(self):
+        fig, ax = plt.subplots(subplot_kw=dict(projection=self.pc))
+        ax.quiver(self.x2d.ravel(), self.y2d.ravel(),
+                  self.u.ravel(), self.v.ravel(), transform=self.rp)
+
+    def test_quiver_transform_xyuv_2d(self):
+        fig, ax = plt.subplots(subplot_kw=dict(projection=self.pc))
+        ax.quiver(self.x2d, self.y2d, self.u, self.v, transform=self.rp)
+
+    def test_quiver_transform_xy_1d_uv_2d(self):
+        fig, ax = plt.subplots(subplot_kw=dict(projection=self.pc))
+        ax.quiver(self.x, self.y, self.u, self.v, transform=self.rp)
+
+    @raises(ValueError)
+    def test_quiver_transform_xy_2d_uv_1d(self):
+        fig, ax = plt.subplots(subplot_kw=dict(projection=self.pc))
+        ax.quiver(self.x2d, self.y2d,
+                  self.u.ravel(), self.v.ravel(), transform=self.rp)
+
+    @raises(ValueError)
+    def test_quiver_transform_inconsistent_shape(self):
+        fig, ax = plt.subplots(subplot_kw=dict(projection=self.pc))
+        ax.quiver(self.x, self.y,
+                  self.u.ravel(), self.v.ravel(), transform=self.rp)