Fixed TimedeltaArray._format_native_types

Author: TomAugspurger

pandas/core/arrays/timedeltas.py

@@ -268,8 +268,11 @@ def _formatter(self, boxed=False):
         from pandas.io.formats.format import _get_format_timedelta64
         return _get_format_timedelta64(self, box=True)
 
-    def _format_native_types(self):
-        return self.astype(object)
+    def _format_native_types(self, na_rep=u'NaT', date_format=None):
+        from pandas.io.formats.format import _get_format_timedelta64
+
+        formatter = _get_format_timedelta64(self._data, na_rep)
+        return np.array([formatter(x) for x in self._data])
 
     # ----------------------------------------------------------------
     # Arithmetic Methods