Backport PR #22975: MNT: fix __array__ to numpy

timhoffm · meeseeksmachine · commit 99b769521189 · 2022-05-18T12:02:08.000Z
diff --git a/lib/matplotlib/cbook/__init__.py b/lib/matplotlib/cbook/__init__.py
@@ -1302,7 +1302,12 @@ def _check_1d(x):
     """Convert scalars to 1D arrays; pass-through arrays as is."""
     # Unpack in case of e.g. Pandas or xarray object
     x = _unpack_to_numpy(x)
-    if not hasattr(x, 'shape') or len(x.shape) < 1:
+    # plot requires `shape` and `ndim`.  If passed an
+    # object that doesn't provide them, then force to numpy array.
+    # Note this will strip unit information.
+    if (not hasattr(x, 'shape') or
+            not hasattr(x, 'ndim') or
+            len(x.shape) < 1):
         return np.atleast_1d(x)
     else:
         return x
diff --git a/lib/matplotlib/tests/test_units.py b/lib/matplotlib/tests/test_units.py
@@ -261,3 +261,22 @@ def test_empty_default_limits(quantity_converter):
     fig.draw_without_rendering()
     assert ax.get_ylim() == (0, 100)
     assert ax.get_xlim() == (28.5, 31.5)
+
+
+# test array-like objects...
+class Kernel:
+    def __init__(self, array):
+        self._array = np.asanyarray(array)
+
+    def __array__(self):
+        return self._array
+
+    @property
+    def shape(self):
+        return self._array.shape
+
+
+def test_plot_kernel():
+    # just a smoketest that fail
+    kernel = Kernel([1, 2, 3, 4, 5])
+    plt.plot(kernel)
