BUG: bug in xs for a Series with a multiindex (GH6258)

doc/source/release.rst

@@ -74,6 +74,7 @@ Bug Fixes
 - Bug in version string gen. for dev versions with shallow clones / install from tarball (:issue:`6127`)
 - Inconsistent tz parsing Timestamp/to_datetime for current year (:issue:`5958`)
 - Indexing bugs with reordered indexes (:issue:`6252`, :issue:`6254`)
+- Bug in ``.xs`` with a Series multiindex (:issue:`6258`, :issue:`5684`)
 
 pandas 0.13.1
 -------------

pandas/core/generic.py

@@ -1262,21 +1262,17 @@ def xs(self, key, axis=0, level=None, copy=True, drop_level=True):
             if not copy and not isinstance(loc, slice):
                 raise ValueError('Cannot retrieve view (copy=False)')
 
-            # level = 0
-            loc_is_slice = isinstance(loc, slice)
-            if not loc_is_slice:
-                indexer = [slice(None)] * self.ndim
-                indexer[axis] = loc
-                indexer = tuple(indexer)
-            else:
-                indexer = loc
+            # convert to a label indexer if needed
+            if isinstance(loc, slice):
                 lev_num = labels._get_level_number(level)
                 if labels.levels[lev_num].inferred_type == 'integer':
-                    indexer = self.index[loc]
+                    loc = labels[loc]
+
+            # create the tuple of the indexer
+            indexer = [slice(None)] * self.ndim
+            indexer[axis] = loc
+            indexer = tuple(indexer)
 
-            # select on the correct axis
-            if axis == 1 and loc_is_slice:
-                indexer = slice(None), indexer
             result = self.ix[indexer]
             setattr(result, result._get_axis_name(axis), new_ax)
             return result

pandas/core/index.py

@@ -3236,7 +3236,7 @@ def _get_level_indexer(self, key, level=0):
         labels = self.labels[level]
 
         if level > 0 or self.lexsort_depth == 0:
-            return labels == loc
+            return np.array(labels == loc,dtype=bool)
         else:
             # sorted, so can return slice object -> view
             i = labels.searchsorted(loc, side='left')

pandas/tests/test_indexing.py

@@ -951,6 +951,24 @@ def test_series_getitem_multiindex(self):
         expected = Series([2,3],index=[1,2])
         assert_series_equal(result,expected)
 
+        # GH6258
+        s = Series([1,3,4,1,3,4],
+                   index=MultiIndex.from_product([list('AB'),
+                                                  list(date_range('20130903',periods=3))]))
+        result = s.xs('20130903',level=1)
+        expected = Series([1,1],index=list('AB'))
+        assert_series_equal(result,expected)
+
+        # GH5684
+        idx = MultiIndex.from_tuples([('a', 'one'), ('a', 'two'),
+                                      ('b', 'one'), ('b', 'two')])
+        s = Series([1, 2, 3, 4], index=idx)
+        s.index.set_names(['L1', 'L2'], inplace=True)
+        result = s.xs('one', level='L2')
+        expected = Series([1, 3], index=['a', 'b'])
+        expected.index.set_names(['L1'], inplace=True)
+        assert_series_equal(result, expected)
+
     def test_ix_general(self):
 
         # ix general issues