From b9c3856d9cdbbfd06168e4e9da28aec3e78b252d Mon Sep 17 00:00:00 2001
From: jreback <jeff@reback.net>
Date: Wed, 18 Jun 2014 11:24:56 -0400
Subject: [PATCH] BUG: Bug in .loc performing fallback integer indexing with
 object dtype indices (GH7496)

---
 doc/source/v0.14.1.txt        |  2 ++
 pandas/core/index.py          |  2 +-
 pandas/tests/test_indexing.py | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/doc/source/v0.14.1.txt b/doc/source/v0.14.1.txt
index 930ba13bef122..01cfa73b8b9f4 100644
--- a/doc/source/v0.14.1.txt
+++ b/doc/source/v0.14.1.txt
@@ -62,6 +62,8 @@ API changes
   when comparing a ``Period`` with another object using ``==`` if the other
   object isn't a ``Period`` ``False`` is returned.
 
+- Bug in ``.loc`` performing fallback integer indexing with ``object`` dtype indices (:issue:`7496`)
+
 .. _whatsnew_0141.prior_deprecations:
 
 Prior Version Deprecations/Changes
diff --git a/pandas/core/index.py b/pandas/core/index.py
index 5956cd7eea9c0..30002a719a556 100644
--- a/pandas/core/index.py
+++ b/pandas/core/index.py
@@ -609,7 +609,7 @@ def _convert_list_indexer_for_mixed(self, keyarr, typ=None):
             and we have a mixed index (e.g. number/labels). figure out
             the indexer. return None if we can't help
         """
-        if com.is_integer_dtype(keyarr) and not self.is_floating():
+        if (typ is None or typ in ['iloc','ix']) and (com.is_integer_dtype(keyarr) and not self.is_floating()):
             if self.inferred_type != 'integer':
                 keyarr = np.where(keyarr < 0,
                                   len(self) + keyarr, keyarr)
diff --git a/pandas/tests/test_indexing.py b/pandas/tests/test_indexing.py
index c074c4333a774..cd569deac2ceb 100644
--- a/pandas/tests/test_indexing.py
+++ b/pandas/tests/test_indexing.py
@@ -806,6 +806,38 @@ def test_loc_to_fail(self):
         # raise a KeyError?
         self.assertRaises(KeyError, df.loc.__getitem__, tuple([[1, 2], [1, 2]]))
 
+        # GH  7496
+        # loc should not fallback
+
+        s = Series()
+        s.loc[1] = 1
+        s.loc['a'] = 2
+
+        self.assertRaises(KeyError, lambda : s.loc[-1])
+
+        result = s.loc[[-1, -2]]
+        expected = Series(np.nan,index=[-1,-2])
+        assert_series_equal(result, expected)
+
+        result = s.loc[['4']]
+        expected = Series(np.nan,index=['4'])
+        assert_series_equal(result, expected)
+
+        s.loc[-1] = 3
+        result = s.loc[[-1,-2]]
+        expected = Series([3,np.nan],index=[-1,-2])
+        assert_series_equal(result, expected)
+
+        s['a'] = 2
+        result = s.loc[[-2]]
+        expected = Series([np.nan],index=[-2])
+        assert_series_equal(result, expected)
+
+        del s['a']
+        def f():
+            s.loc[[-2]] = 0
+        self.assertRaises(KeyError, f)
+
     def test_loc_getitem_label_slice(self):
 
         # label slices (with ints)