FIX: support pandas 0.25

closes matplotlib#14992

Author: tacaswell

lib/matplotlib/cbook/__init__.py

@@ -1326,7 +1326,11 @@ def _check_1d(x):
         return np.atleast_1d(x)
     else:
         try:
-            x[:, None]
+            shape = x[:, None].shape
+            # work around https://github.com/pandas-dev/pandas/issues/27775
+            # which mean the shape is not as expected
+            if len(shape) != 2:
+                return np.atleast_1d(x)
             return x
         except (IndexError, TypeError):
             return np.atleast_1d(x)

lib/matplotlib/tests/test_axes.py

@@ -5552,6 +5552,12 @@ def test_pandas_errorbar_indexing(pd):
     ax.errorbar('x', 'y', xerr='xe', yerr='ye', data=df)
 
 
+def test_pandas_index_shape(pd):
+    df = pd.DataFrame({"XX" : [4,5,6], "YY" : [7,1,2]})
+    fig, ax = plt.subplots()
+    ax.plot(df.index, df['YY'])
+
+
 def test_pandas_indexing_hist(pd):
     ser_1 = pd.Series(data=[1, 2, 2, 3, 3, 4, 4, 4, 4, 5])
     ser_2 = ser_1.iloc[1:]