BUG: Series.get() with ExtensionArray and integer index

doc/source/whatsnew/v0.24.0.txt

@@ -270,6 +270,7 @@ Reshaping
 ExtensionArray
 ^^^^^^^^^^^^^^
 
+- Bug in :meth:`Series.get` for ``Series`` using ``ExtensionArray`` and integer index (:issue:`21257`)
 - :meth:`Series.combine()` works correctly with :class:`~pandas.api.extensions.ExtensionArray` inside of :class:`Series` (:issue:`20825`)
 - :meth:`Series.combine()` with scalar argument now works for any function type (:issue:`21248`)
 -

pandas/core/indexes/base.py

@@ -2988,16 +2988,20 @@ def get_value(self, series, key):
         # use this, e.g. DatetimeIndex
         s = getattr(series, '_values', None)
         if isinstance(s, (ExtensionArray, Index)) and is_scalar(key):
-            # GH 20825
+            # GH 20882, 21257
             # Unify Index and ExtensionArray treatment
             # First try to convert the key to a location
-            # If that fails, see if key is an integer, and
+            # If that fails, raise a KeyError if an integer
+            # index, otherwise, see if key is an integer, and
             # try that
             try:
                 iloc = self.get_loc(key)
                 return s[iloc]
             except KeyError:
-                if is_integer(key):
+                if (len(self) > 0 and
+                        self.inferred_type in ['integer', 'boolean']):
+                    raise
+                elif is_integer(key):
                     return s[key]
 
         s = com._values_from_object(series)

pandas/tests/extension/base/getitem.py

@@ -130,7 +130,7 @@ def test_get(self, data):
         expected = s.iloc[[0, 1]]
         self.assert_series_equal(result, expected)
 
-        assert s.get(-1) == s.iloc[-1]
+        assert s.get(-1) is None
         assert s.get(s.index.max() + 1) is None
 
         s = pd.Series(data[:6], index=list('abcdef'))
@@ -147,6 +147,11 @@ def test_get(self, data):
         assert s.get(-1) == s.iloc[-1]
         assert s.get(len(s)) is None
 
+        # GH 21257
+        s = pd.Series(data)
+        s2 = s[::2]
+        assert s2.get(1) is None
+
     def test_take_sequence(self, data):
         result = pd.Series(data)[[0, 1, 3]]
         assert result.iloc[0] == data[0]

pandas/tests/series/indexing/test_indexing.py

@@ -187,6 +187,49 @@ def test_getitem_box_float64(test_data):
     assert isinstance(value, np.float64)
 
 
+@pytest.mark.parametrize(
+    'arr',
+    [
+        np.random.randn(10),
+        tm.makeDateIndex(10, name='a').tz_localize(
+            tz='US/Eastern'),
+    ])
+def test_get(arr):
+    # GH 21260
+    s = Series(arr, index=[2 * i for i in range(len(arr))])
+    assert s.get(4) == s.iloc[2]
+
+    result = s.get([4, 6])
+    expected = s.iloc[[2, 3]]
+    tm.assert_series_equal(result, expected)
+
+    result = s.get(slice(2))
+    expected = s.iloc[[0, 1]]
+    tm.assert_series_equal(result, expected)
+
+    assert s.get(-1) is None
+    assert s.get(s.index.max() + 1) is None
+
+    s = Series(arr[:6], index=list('abcdef'))
+    assert s.get('c') == s.iloc[2]
+
+    result = s.get(slice('b', 'd'))
+    expected = s.iloc[[1, 2, 3]]
+    tm.assert_series_equal(result, expected)
+
+    result = s.get('Z')
+    assert result is None
+
+    assert s.get(4) == s.iloc[4]
+    assert s.get(-1) == s.iloc[-1]
+    assert s.get(len(s)) is None
+
+    # GH 21257
+    s = pd.Series(arr)
+    s2 = s[::2]
+    assert s2.get(1) is None
+
+
 def test_series_box_timestamp():
     rng = pd.date_range('20090415', '20090519', freq='B')
     ser = Series(rng)