BUG: Cast ExtensionArray to numpy ndarray before plot

doc/source/whatsnew/v0.24.2.rst

@@ -31,6 +31,7 @@ Fixed Regressions
 - Fixed regression in ``IntervalDtype`` construction where passing an incorrect string with 'Interval' as a prefix could result in a ``RecursionError``. (:issue:`25338`)
 - Fixed regression in :class:`Categorical`, where constructing it from a categorical ``Series`` and an explicit ``categories=`` that differed from that in the ``Series`` created an invalid object which could trigger segfaults. (:issue:`25318`)
 - Fixed pip installing from source into an environment without NumPy (:issue:`25193`)
+- Fixed bug where :class:`api.extensions.ExtensionArray` could not be used in matplotlib plotting (:issue:`25587`)
 
 .. _whatsnew_0242.enhancements:
 

pandas/plotting/_core.py

@@ -15,11 +15,13 @@
 from pandas.util._decorators import Appender, cache_readonly
 
 from pandas.core.dtypes.common import (
-    is_hashable, is_integer, is_iterator, is_list_like, is_number)
+    is_hashable, is_integer, is_iterator, is_list_like, is_number,
+    is_extension_array_dtype)
 from pandas.core.dtypes.generic import (
     ABCDataFrame, ABCIndexClass, ABCMultiIndex, ABCPeriodIndex, ABCSeries)
 from pandas.core.dtypes.missing import isna, notna, remove_na_arraylike
 
+from pandas.core.arrays import ExtensionArray
 from pandas.core.base import PandasObject
 import pandas.core.common as com
 from pandas.core.config import get_option
@@ -574,6 +576,13 @@ def _get_xticks(self, convert_period=False):
 
     @classmethod
     def _plot(cls, ax, x, y, style=None, is_errorbar=False, **kwds):
+        # GH25587: cast ExtensionArray of pandas (IntegerArray, etc.) to
+        # np.ndarray before plot.
+        if is_extension_array_dtype(x):
+            x = np.asarray(x)
+        if is_extension_array_dtype(y):
+            y = np.asarray(y)
+
         mask = isna(y)
         if mask.any():
             y = np.ma.array(y)
@@ -1792,7 +1801,6 @@ def _plot(data, x=None, y=None, subplots=False,
                         )
                     label_name = label_kw or data.columns
                     data.columns = label_name
-
         plot_obj = klass(data, subplots=subplots, ax=ax, kind=kind, **kwds)
 
     plot_obj.generate()

pandas/tests/plotting/test_frame.py

@@ -144,8 +144,17 @@ def test_plot(self):
         result = ax.axes
         assert result is axes[0]
 
-    # GH 15516
+    @pytest.mark.parametrize("kwargs", [
+        dict(yticks=[1, 2, 3, 4]),
+        dict(xticks=[4, 5, 3, 2])
+    ])
+    def test_integer_array_plot(self, kwargs):
+        # GH 25587
+        s = Series([4, 5, 3, 2], dtype="UInt32")
+        _check_plot_works(s.plot, **kwargs)
+
     def test_mpl2_color_cycle_str(self):
+        # GH 15516
         colors = ['C' + str(x) for x in range(10)]
         df = DataFrame(randn(10, 3), columns=['a', 'b', 'c'])
         for c in colors: