Add angle kwarg to patches.Rectangle

doc/users/whats_new.rst

@@ -20,6 +20,11 @@ revision, see the :ref:`github-stats`.
 new in matplotlib-1.3
 =====================
 
+Initialize a rotated rectangle
+------------------------------
+Damon McDougall extended the :class:`~matplotlib.patches.Rectangle` constructor
+to accept an `angle` kwarg, specifying the rotation of a rectangle in degrees.
+
 Rectangular colorbar extensions
 -------------------------------
 Andrew Dawson added a new keyword argument *extendrect* to

lib/matplotlib/patches.py

@@ -539,9 +539,12 @@ def __str__(self):
             + "(%g,%g;%gx%g)" % (self._x, self._y, self._width, self._height)
 
     @docstring.dedent_interpd
-    def __init__(self, xy, width, height, **kwargs):
+    def __init__(self, xy, width, height, angle=0.0, **kwargs):
         """
 
+        *angle*
+          rotation in degrees (anti-clockwise)
+
         *fill* is a boolean indicating whether to fill the rectangle
 
         Valid kwargs are:
@@ -554,6 +557,7 @@ def __init__(self, xy, width, height, **kwargs):
         self._y = xy[1]
         self._width = width
         self._height = height
+        self._angle = angle
         # Note: This cannot be calculated until this is added to an Axes
         self._rect_transform = transforms.IdentityTransform()
 
@@ -574,7 +578,10 @@ def _update_patch_transform(self):
         width = self.convert_xunits(self._width)
         height = self.convert_yunits(self._height)
         bbox = transforms.Bbox.from_bounds(x, y, width, height)
+        rot_trans = transforms.Affine2D()
+        rot_trans.rotate_deg_around(x, y, self._angle)
         self._rect_transform = transforms.BboxTransformTo(bbox)
+        self._rect_transform += rot_trans
 
     def get_patch_transform(self):
         self._update_patch_transform()

lib/matplotlib/tests/test_patches.py

@@ -2,8 +2,11 @@
 Tests specific to the patches module.
 """
 
+import numpy as np
 from numpy.testing import assert_array_equal
+from numpy.testing import assert_almost_equal
 from matplotlib.patches import Polygon
+from matplotlib.patches import Rectangle
 
 def test_Polygon_close():
     """
@@ -40,3 +43,25 @@ def test_Polygon_close():
     p.set_xy(xyclosed)
     assert_array_equal(p.get_xy(), xyclosed)
 
+def test_rotate_rect():
+    loc = np.asarray([1.0, 2.0])
+    width = 2
+    height = 3
+    angle = 30.0
+
+    # A rotated rectangle
+    rect1 = Rectangle(loc, width, height, angle=angle)
+
+    # A non-rotated rectangle
+    rect2 = Rectangle(loc, width, height)
+
+    # Set up an explicit rotation matrix (in radians)
+    angle_rad = np.pi * angle / 180.0
+    rotation_matrix = np.array([[np.cos(angle_rad), -np.sin(angle_rad)],
+                                [np.sin(angle_rad),  np.cos(angle_rad)]])
+
+    # Translate to origin, rotate each vertex, and then translate back
+    new_verts = np.inner(rotation_matrix, rect2.get_verts() - loc).T + loc
+
+    # They should be the same
+    assert_almost_equal(rect1.get_verts(), new_verts)