Merge pull request pandas-dev#6790 from jreback/slice

BUG: bug in taking all on a multi-index when only level 0 is specified (GH6788)

Author: jreback

pandas/core/indexing.py

@@ -1040,6 +1040,10 @@ def _convert_to_indexer(self, obj, axis=0, is_setter=False):
                     level = 0
                     _, indexer = labels.reindex(objarr, level=level)
 
+                    # take all
+                    if indexer is None:
+                        indexer = np.arange(len(labels))
+
                     check = labels.levels[0].get_indexer(objarr)
                 else:
                     level = None

pandas/tests/test_indexing.py

@@ -1128,6 +1128,17 @@ def test_loc_multiindex(self):
         xp = mi_int.ix[4]
         assert_frame_equal(rs,xp)
 
+        # GH6788
+        # multi-index indexer is None (meaning take all)
+        attributes = ['Attribute' + str(i) for i in range(1)]
+        attribute_values = ['Value' + str(i) for i in range(5)]
+
+        index = MultiIndex.from_product([attributes,attribute_values])
+        df = 0.1 * np.random.randn(10, 1 * 5) + 0.5
+        df = DataFrame(df, columns=index)
+        result = df[attributes]
+        assert_frame_equal(result, df)
+
     def test_series_getitem_multiindex(self):
 
         # GH 6018