BUG: DatetimeIndex.intersection issue with equal unanchored offsets c…

…lose #1708

RELEASE.rst

@@ -39,6 +39,7 @@ pandas 0.8.2
 **Bug fixes**
 
   - Fix critical DatetimeIndex.union bugs (#1730, #1719, #1745, #1702)
+  - Fix critical DatetimeIndex.intersection bug with unanchored offsets (#1708)
   - Fix MM-YYYY time series indexing case (#1672)
   - Fix case where Categorical group key was not being passed into index in
     GroupBy result (#1701)

pandas/tseries/index.py

@@ -834,6 +834,7 @@ def intersection(self, other):
 
         elif (other.offset is None or self.offset is None or
               other.offset != self.offset or
+              not other.offset.isAnchored() or
               (not self.is_monotonic or not other.is_monotonic)):
             result = Index.intersection(self, other)
             if isinstance(result, DatetimeIndex):

pandas/tseries/tests/test_timeseries.py

@@ -1179,6 +1179,14 @@ def test_union_bug_1745(self):
         exp = DatetimeIndex(sorted(set(list(left)) | set(list(right))))
         self.assert_(result.equals(exp))
 
+    def test_intersection_bug_1708(self):
+        from pandas import DateOffset
+        index_1 = date_range('1/1/2012', periods=4, freq='12H')
+        index_2 = index_1 + DateOffset(hours=1)
+
+        result = index_1 & index_2
+        self.assertEqual(len(result), 0)
+
     # def test_add_timedelta64(self):
     #     rng = date_range('1/1/2000', periods=5)
     #     delta = rng.values[3] - rng.values[1]