Merge pull request matplotlib#22018 from jakevdp/fix-hist-iter

BUG: fix handling of zero-dimensional arrays in cbook._reshape_2D

Author: tacaswell

lib/matplotlib/cbook/__init__.py

@@ -1389,9 +1389,13 @@ def _reshape_2D(X, name):
     for xi in X:
         # check if this is iterable, except for strings which we
         # treat as singletons.
-        if (isinstance(xi, collections.abc.Iterable) and
-                not isinstance(xi, str)):
-            is_1d = False
+        if not isinstance(xi, str):
+            try:
+                iter(xi)
+            except TypeError:
+                pass
+            else:
+                is_1d = False
         xi = np.asanyarray(xi)
         nd = np.ndim(xi)
         if nd > 1:

lib/matplotlib/tests/test_cbook.py

@@ -610,6 +610,13 @@ class Dummy:
     assert isinstance(xnew[1], np.ndarray) and xnew[1].shape == (1,)
     assert isinstance(xnew[2], np.ndarray) and xnew[2].shape == (1,)
 
+    # Test a list of zero-dimensional arrays
+    x = [np.array(0), np.array(1), np.array(2)]
+    xnew = cbook._reshape_2D(x, 'x')
+    assert isinstance(xnew, list)
+    assert len(xnew) == 1
+    assert isinstance(xnew[0], np.ndarray) and xnew[0].shape == (3,)
+
     # Now test with a list of lists with different lengths, which means the
     # array will internally be converted to a 1D object array of lists
     x = [[1, 2, 3], [3, 4], [2]]