BUG: Bug in multi-axis indexing using .loc on non-unique indices (GH6504)

doc/source/release.rst

@@ -190,6 +190,7 @@ Bug Fixes
  rest of pandas (:issue:`5129`).
 - Bug in ``read_html`` tests where redirected invalid URLs would make one test
  fail (:issue:`6445`).
+- Bug in multi-axis indexing using ``.loc`` on non-unique indices (:issue:`6504`)
 
 pandas 0.13.1
 -------------

pandas/core/indexing.py

@@ -710,6 +710,8 @@ def _multi_take_opportunity(self, tup):
  return False
  elif com._is_bool_indexer(indexer):
  return False
+ elif not ax.is_unique:
+ return False
 
  return True
 

pandas/tests/test_indexing.py

@@ -1599,6 +1599,21 @@ def test_dups_fancy_indexing(self):
  result = df.ix[:,['A','B','C']]
  assert_frame_equal(result, expected)
 
+ # GH 6504, multi-axis indexing
+ df = DataFrame(np.random.randn(9,2), index=[1,1,1,2,2,2,3,3,3], columns=['a', 'b'])
+
+ expected = df.iloc[0:6]
+ result = df.loc[[1, 2]]
+ assert_frame_equal(result, expected)
+
+ expected = df
+ result = df.loc[:,['a', 'b']]
+ assert_frame_equal(result, expected)
+
+ expected = df.iloc[0:6,:]
+ result = df.loc[[1, 2], ['a', 'b']]
+ assert_frame_equal(result, expected)
+
  def test_indexing_mixed_frame_bug(self):
 
  # GH3492