Don't allow shape mismatches for empty arrays

Instead change callers to have empty arrays of the right shape.

Author: jkseppan

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/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/numpy_cpp.h

@@ -448,12 +448,6 @@ class array_view : public detail::array_view_accessors<array_view, T, ND>
 		    return 1;
 		}
             }
-	    if (PyArray_NDIM(tmp) > 0 && PyArray_DIM(tmp, 0) == 0) {
-		// accept dimension mismatch for empty arrays
-		Py_XDECREF(m_arr);
-		m_arr = tmp;
-		return 1;
-	    }
 	    if (PyArray_NDIM(tmp) != ND) {
 		PyErr_Format(PyExc_ValueError,
 			     "Expected %d-dimensional array, got %d",