FIX: array_view construction for empty arrays

lib/matplotlib/cbook.py

@@ -2244,6 +2244,21 @@ def _reshape_2D(X):
     return X
 
 
+def ensure_3d(arr):
+    """
+    Return a version of arr with ndim==3, with extra dimensions added
+    at the end of arr.shape as needed.
+    """
+    arr = np.asanyarray(arr)
+    if arr.ndim == 1:
+        arr = arr[:, None, None]
+    elif arr.ndim == 2:
+        arr = arr[:, :, None]
+    elif arr.ndim > 3 or arr.ndim < 1:
+        raise ValueError("cannot convert arr to 3-dimensional")
+    return arr
+
+
 def violin_stats(X, method, points=100):
     '''
     Returns a list of dictionaries of data which can be used to draw a series

lib/matplotlib/collections.py

@@ -80,9 +80,7 @@ class Collection(artist.Artist, cm.ScalarMappable):
     # _offsets must be a Nx2 array!
     _offsets.shape = (0, 2)
     _transOffset = transforms.IdentityTransform()
-    _transforms = []
-
-
+    _transforms = np.empty((0, 3, 3))
 
     def __init__(self,
                  edgecolors=None,
@@ -1515,7 +1513,7 @@ def __init__(self, widths, heights, angles, units='points', **kwargs):
         self._angles = np.asarray(angles).ravel() * (np.pi / 180.0)
         self._units = units
         self.set_transform(transforms.IdentityTransform())
-        self._transforms = []
+        self._transforms = np.empty((0, 3, 3))
         self._paths = [mpath.Path.unit_circle()]
 
     def _set_transforms(self):

lib/matplotlib/path.py

@@ -24,7 +24,7 @@
 from numpy import ma
 
 from matplotlib import _path
-from matplotlib.cbook import simple_linear_interpolation, maxdict
+from matplotlib.cbook import simple_linear_interpolation, maxdict, ensure_3d
 from matplotlib import rcParams
 
 
@@ -988,7 +988,8 @@ def get_path_collection_extents(
     if len(paths) == 0:
         raise ValueError("No paths provided")
     return Bbox.from_extents(*_path.get_path_collection_extents(
-        master_transform, paths, transforms, offsets, offset_transform))
+        master_transform, paths, ensure_3d(transforms),
+        offsets, offset_transform))
 
 
 def get_paths_extents(paths, transforms=[]):

lib/matplotlib/tests/test_cbook.py

@@ -376,3 +376,11 @@ def test_step_fails():
                   np.arange(12))
     assert_raises(ValueError, cbook._step_validation,
                   np.arange(12), np.arange(3))
+
+
+def test_ensure_3d():
+    assert_array_equal([[[1]], [[2]], [[3]]],
+                       cbook.ensure_3d([1, 2, 3]))
+    assert_array_equal([[[1], [2]], [[3], [4]]],
+                       cbook.ensure_3d([[1, 2], [3, 4]]))
+    assert_raises(ValueError, cbook.ensure_3d, [[[[1]]]])

lib/matplotlib/tests/test_transforms.py

@@ -561,6 +561,21 @@ def test_nonsingular():
         assert_array_equal(out, zero_expansion)
 
 
+def test_invalid_arguments():
+    t = mtrans.Affine2D()
+    # There are two different exceptions, since the wrong number of
+    # dimensions is caught when constructing an array_view, and that
+    # raises a ValueError, and a wrong shape with a possible number
+    # of dimensions is caught by our CALL_CPP macro, which always
+    # raises the less precise RuntimeError.
+    assert_raises(ValueError, t.transform, 1)
+    assert_raises(ValueError, t.transform, [[[1]]])
+    assert_raises(RuntimeError, t.transform, [])
+    assert_raises(RuntimeError, t.transform, [1])
+    assert_raises(RuntimeError, t.transform, [[1]])
+    assert_raises(RuntimeError, t.transform, [[1, 2, 3]])
+
+
 if __name__ == '__main__':
     import nose
     nose.runmodule(argv=['-s', '--with-doctest'],  exit=False)

lib/matplotlib/transforms.py

@@ -48,6 +48,7 @@
     from sets import Set as set
 
 from .path import Path
+from .cbook import ensure_3d
 
 DEBUG = False
 # we need this later, but this is very expensive to set up
@@ -666,7 +667,8 @@ def count_overlaps(self, bboxes):
 
         bboxes is a sequence of :class:`BboxBase` objects
         """
-        return count_bboxes_overlapping_bbox(self, [np.array(x) for x in bboxes])
+        return count_bboxes_overlapping_bbox(
+            self, ensure_3d([np.array(x) for x in bboxes]))
 
     def expanded(self, sw, sh):
         """

src/_path_wrapper.cpp

@@ -439,11 +439,16 @@ static PyObject *Py_affine_transform(PyObject *self, PyObject *args, PyObject *k
         CALL_CPP("affine_transform", (affine_transform_2d(vertices, trans, result)));
         return result.pyobj();
     } catch (py::exception) {
-        numpy::array_view<double, 1> vertices(vertices_obj);
-        npy_intp dims[] = { vertices.dim(0) };
-        numpy::array_view<double, 1> result(dims);
-        CALL_CPP("affine_transform", (affine_transform_1d(vertices, trans, result)));
-        return result.pyobj();
+        PyErr_Clear();
+        try {
+            numpy::array_view<double, 1> vertices(vertices_obj);
+            npy_intp dims[] = { vertices.dim(0) };
+            numpy::array_view<double, 1> result(dims);
+            CALL_CPP("affine_transform", (affine_transform_1d(vertices, trans, result)));
+            return result.pyobj();
+        } catch (py::exception) {
+            return NULL;
+        }
     }
 }
 

src/numpy_cpp.h

@@ -443,13 +443,18 @@ class array_view : public detail::array_view_accessors<array_view, T, ND>
                 m_data = NULL;
                 m_shape = zeros;
                 m_strides = zeros;
-            } else if (PyArray_NDIM(tmp) != ND) {
-                PyErr_Format(PyExc_ValueError,
-                             "Expected %d-dimensional array, got %d",
-                             ND,
-                             PyArray_NDIM(tmp));
-                Py_DECREF(tmp);
-                return 0;
+		if (PyArray_NDIM(tmp) == 0 && ND == 0) {
+		    m_arr = tmp;
+		    return 1;
+		}
+            }
+	    if (PyArray_NDIM(tmp) != ND) {
+		PyErr_Format(PyExc_ValueError,
+			     "Expected %d-dimensional array, got %d",
+			     ND,
+			     PyArray_NDIM(tmp));
+		Py_DECREF(tmp);
+		return 0;
             }
 
             /* Copy some of the data to the view object for faster access */