Merge branch 'master' of https://github.com/pandas-dev/pandas into id…

…x_nat_ops

pandas/core/indexes/datetimes.py

@@ -855,7 +855,14 @@ def __setstate__(self, state):
 
     def _sub_datelike(self, other):
         # subtract a datetime from myself, yielding a ndarray[timedelta64[ns]]
-        if isinstance(other, DatetimeIndex):
+        if isinstance(other, (DatetimeIndex, np.ndarray)):
+            # if other is an ndarray, we assume it is datetime64-dtype
+            other = DatetimeIndex(other)
+            # require tz compat
+            if not self._has_same_tz(other):
+                raise TypeError("{cls} subtraction must have the same "
+                                "timezones or no timezones"
+                                .format(cls=type(self).__name__))
             result = self._sub_datelike_dti(other)
         elif isinstance(other, (datetime, np.datetime64)):
             assert other is not libts.NaT
@@ -873,19 +880,15 @@ def _sub_datelike(self, other):
                 result = self._maybe_mask_results(result,
                                                   fill_value=libts.iNaT)
         else:
-            raise TypeError("cannot subtract DatetimeIndex and {typ}"
-                            .format(typ=type(other).__name__))
+            raise TypeError("cannot subtract {cls} and {typ}"
+                            .format(cls=type(self).__name__,
+                                    typ=type(other).__name__))
         return result.view('timedelta64[ns]')
 
     def _sub_datelike_dti(self, other):
         """subtraction of two DatetimeIndexes"""
         if not len(self) == len(other):
             raise ValueError("cannot add indices of unequal length")
-        elif not self._has_same_tz(other):
-            # require tz compat
-            raise TypeError("{cls} subtraction must have the same "
-                            "timezones or no timezones"
-                            .format(cls=type(self).__name__))
 
         self_i8 = self.asi8
         other_i8 = other.asi8

pandas/core/indexes/timedeltas.py

@@ -414,17 +414,24 @@ def _evaluate_with_timedelta_like(self, other, op):
     def _add_datelike(self, other):
         # adding a timedeltaindex to a datetimelike
         from pandas import Timestamp, DatetimeIndex
-        assert other is not NaT
-        other = Timestamp(other)
-        i8 = self.asi8
-        result = checked_add_with_arr(i8, other.value,
-                                      arr_mask=self._isnan)
-        result = self._maybe_mask_results(result, fill_value=iNaT)
-        return DatetimeIndex(result)
+        if isinstance(other, (DatetimeIndex, np.ndarray)):
+            # if other is an ndarray, we assume it is datetime64-dtype
+            # defer to implementation in DatetimeIndex
+            other = DatetimeIndex(other)
+            return other + self
+        else:
+            assert other is not NaT
+            other = Timestamp(other)
+            i8 = self.asi8
+            result = checked_add_with_arr(i8, other.value,
+                                          arr_mask=self._isnan)
+            result = self._maybe_mask_results(result, fill_value=iNaT)
+            return DatetimeIndex(result)
 
     def _sub_datelike(self, other):
         assert other is not NaT
-        raise TypeError("cannot subtract a datelike from a TimedeltaIndex")
+        raise TypeError("cannot subtract a datelike from a {cls}"
+                        .format(cls=type(self).__name__))
 
     def _addsub_offset_array(self, other, op):
         # Add or subtract Array-like of DateOffset objects