BUG: Int64Index.take and MultiIndex.take don't lost names, GH #262

Author: wesm

RELEASE.rst

@@ -158,6 +158,8 @@ feedback on the library.
   - `DataFrame.iteritems` and `DataFrame._series` not assigning name attribute
   - Panel.__repr__ raised exception on length-0 major/minor axes
   - `DataFrame.join` on key with empty DataFrame produced incorrect columns
+  - `Int64Index.take` and `MultiIndex.take` lost name field, fix downstream
+    issue GH #262
   - `read_csv` / `read_table` fixes
     - Be less aggressive about converting float->int in cases of floating point
       representations of integers like 1.0, 2.0, etc.

pandas/core/index.py

@@ -759,7 +759,7 @@ def take(self, *args, **kwargs):
         Analogous to ndarray.take
         """
         taken = self.values.take(*args, **kwargs)
-        return Int64Index(taken)
+        return Int64Index(taken, name=self.name)
 
 class DateIndex(Index):
     pass
@@ -1064,7 +1064,8 @@ def take(self, *args, **kwargs):
         Analogous to ndarray.take
         """
         new_labels = [lab.take(*args, **kwargs) for lab in self.labels]
-        return MultiIndex(levels=self.levels, labels=new_labels)
+        return MultiIndex(levels=self.levels, labels=new_labels,
+                          names=self.names)
 
     def append(self, other):
         """

pandas/tests/test_index.py

@@ -556,6 +556,11 @@ def test_prevent_casting(self):
         result = self.index.astype('O')
         self.assert_(result.dtype == np.object_)
 
+    def test_take_preserve_name(self):
+        index = Int64Index([1,2,3,4], name='foo')
+        taken = index.take([3,0,1])
+        self.assertEqual(index.name, taken.name)
+
 class TestMultiIndex(unittest.TestCase):
 
     def setUp(self):
@@ -967,6 +972,10 @@ def test_insert(self):
         # key wrong length
         self.assertRaises(Exception, self.index.insert, 0, ('foo2',))
 
+    def test_take_preserve_name(self):
+        taken = self.index.take([3,0,1])
+        self.assertEqual(taken.names, self.index.names)
+
 class TestFactor(unittest.TestCase):
 
     def setUp(self):

pandas/tests/test_multilevel.py

@@ -75,6 +75,10 @@ def test_reindex_preserve_levels(self):
         chunk = ymdT.ix[:, new_index]
         self.assert_(chunk.columns is new_index)
 
+    def test_sort_index_preserve_levels(self):
+        result = self.frame.sort_index()
+        self.assertEquals(result.index.names, self.frame.index.names)
+
     def test_repr_to_string(self):
         repr(self.frame)
         repr(self.ymd)