BUG: Fix Series.get() for ExtensionArray and Categorical (pandas-dev#20885)

Author: Dr-Irv

pandas/core/indexes/base.py

@@ -3082,12 +3082,17 @@ 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
+ # Unify Index and ExtensionArray treatment
+ # First try to convert the key to a location
+ # If that fails, see if key is an integer, and
+ # try that
  try:
- return s[key]
- except (IndexError, ValueError):
-
- # invalid type as an indexer
- pass
+ iloc = self.get_loc(key)
+  return s[iloc]
+ except KeyError:
+ if is_integer(key):
+  return s[key]
 
  s = com._values_from_object(series)
  k = com._values_from_object(key)

pandas/tests/extension/base/getitem.py

@@ -117,6 +117,36 @@ def test_getitem_slice(self, data):
  result = data[slice(1)] # scalar
  assert isinstance(result, type(data))
 
+ def test_get(self, data):
+ # GH 20882
+ s = pd.Series(data, index=[2 * i for i in range(len(data))])
+ assert s.get(4) == s.iloc[2]
+
+ result = s.get([4, 6])
+ expected = s.iloc[[2, 3]]
+ self.assert_series_equal(result, expected)
+
+ result = s.get(slice(2))
+ expected = s.iloc[[0, 1]]
+ self.assert_series_equal(result, expected)
+
+ assert s.get(-1) == s.iloc[-1]
+ assert s.get(s.index.max() + 1) is None
+
+ s = pd.Series(data[:6], index=list('abcdef'))
+ assert s.get('c') == s.iloc[2]
+
+ result = s.get(slice('b', 'd'))
+ expected = s.iloc[[1, 2, 3]]
+ self.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
+
  def test_take_sequence(self, data):
  result = pd.Series(data)[[0, 1, 3]]
  assert result.iloc[0] == data[0]