BUG: Bug in Index construction with a mixed list of tuples #10697)

Author: jreback

doc/source/whatsnew/v0.17.0.txt

@@ -367,7 +367,7 @@ Bug Fixes
 - Bug in ``Index.drop_duplicates`` dropping name(s) (:issue:`10115`)
 - Bug in ``pd.Series`` when setting a value on an empty ``Series`` whose index has a frequency. (:issue:`10193`)
 - Bug in ``DataFrame.plot`` raises ``ValueError`` when color name is specified by multiple characters (:issue:`10387`)
-
+- Bug in ``Index`` construction with a mixed list of tuples (:issue:`10697`)
 - Bug in ``DataFrame.reset_index`` when index contains `NaT`. (:issue:`10388`)
 - Bug in ``ExcelReader`` when worksheet is empty (:issue:`6403`)
 - Bug in ``Table.select_column`` where name is not preserved (:issue:`10392`)

pandas/core/index.py

@@ -164,16 +164,21 @@ def __new__(cls, data=None, dtype=None, copy=False, name=None, fastpath=False,
             cls._scalar_data_error(data)
         else:
             if tupleize_cols and isinstance(data, list) and data and isinstance(data[0], tuple):
-                try:
 
-                    # must be orderable in py3
-                    if compat.PY3:
-                        sorted(data)
-                    return MultiIndex.from_tuples(
-                        data, names=name or kwargs.get('names'))
-                except (TypeError, KeyError):
-                    # python2 - MultiIndex fails on mixed types
-                    pass
+                # we must be all tuples, otherwise don't construct
+                # 10697
+                if all( isinstance(e, tuple) for e in data ):
+
+                    try:
+
+                        # must be orderable in py3
+                        if compat.PY3:
+                            sorted(data)
+                        return MultiIndex.from_tuples(
+                            data, names=name or kwargs.get('names'))
+                    except (TypeError, KeyError):
+                        # python2 - MultiIndex fails on mixed types
+                        pass
 
             # other iterable of some kind
             subarr = com._asarray_tuplesafe(data, dtype=object)

pandas/tests/test_index.py

@@ -553,6 +553,15 @@ def test_constructor_corner(self):
         # corner case
         self.assertRaises(TypeError, Index, 0)
 
+    def test_consruction_list_mixed_tuples(self):
+        # 10697
+        # if we are constructing from a mixed list of tuples, make sure that we
+        # are independent of the sorting order
+        idx1 = Index([('A',1),'B'])
+        self.assertIsInstance(idx1, Index) and self.assertNotInstance(idx1, MultiIndex)
+        idx2 = Index(['B',('A',1)])
+        self.assertIsInstance(idx2, Index) and self.assertNotInstance(idx2, MultiIndex)
+
     def test_constructor_from_series(self):
 
         expected = DatetimeIndex([Timestamp('20110101'),Timestamp('20120101'),Timestamp('20130101')])

pandas/tools/tests/test_merge.py

@@ -2002,6 +2002,13 @@ def test_dups_index(self):
         result = df.append(df)
         assert_frame_equal(result, expected)
 
+    def test_with_mixed_tuples(self):
+        # 10697
+        # columns have mixed tuples, so handle properly
+        df1 = DataFrame({ u'A' : 'foo', (u'B',1) : 'bar' },index=range(2))
+        df2 = DataFrame({ u'B' : 'foo', (u'B',1) : 'bar' },index=range(2))
+        result = concat([df1,df2])
+
     def test_join_dups(self):
 
         # joining dups