BUG: index name in to_records #2161

pandas/core/frame.py

@@ -923,7 +923,16 @@ def to_records(self, index=True):
         if index:
             arrays = [self.index.values] + [self[c].values
                                             for c in self.columns]
-            names = ['index'] + list(map(str, self.columns))
+            count = 0
+            index_names = self.index.names
+            if isinstance(self.index, MultiIndex):
+                for i, n in enumerate(index_names):
+                    if n is None:
+                        index_names[i] = 'level_%d' % count
+                        count += 1
+            elif index_names[0] is None:
+                index_names = ['index']
+            names = index_names + list(map(str, self.columns))
         else:
             arrays = [self[c].values for c in self.columns]
             names = list(map(str, self.columns))

pandas/tests/test_frame.py

@@ -2572,6 +2572,21 @@ def test_to_records_floats(self):
         df = DataFrame(np.random.rand(10,10))
         df.to_records()
 
+    def test_to_recods_index_name(self):
+        df = DataFrame(np.random.randn(3, 3))
+        df.index.name = 'X'
+        rs = df.to_records()
+        self.assert_('X' in rs.dtype.fields)
+
+        df = DataFrame(np.random.randn(3, 3))
+        rs = df.to_records()
+        self.assert_('index' in rs.dtype.fields)
+
+        df.index = MultiIndex.from_tuples([('a', 'x'), ('a', 'y'), ('b', 'z')])
+        df.index.names = ['A', None]
+        rs = df.to_records()
+        self.assert_('level_0' in rs.dtype.fields)
+
     def test_join_str_datetime(self):
         str_dates = ['20120209' , '20120222']
         dt_dates = [datetime(2012,2,9), datetime(2012,2,22)]