BUG: Fix irregular Timestamp arithmetic types pandas-dev#6543

Author: rosnfeld

doc/source/release.rst

@@ -185,7 +185,7 @@ Bug Fixes
 - Bug in :meth:`DataFrame.replace` where nested dicts were erroneously
   depending on the order of dictionary keys and values (:issue:`5338`).
 - Perf issue in concatting with empty objects (:issue:`3259`)
-- Clarify sorting of ``sym_diff`` on ``Index``es with ``NaN``s (:isssue:`6444`)
+- Clarify sorting of ``sym_diff`` on ``Index``es with ``NaN``s (:issue:`6444`)
 - Regression in ``MultiIndex.from_product`` with a ``DatetimeIndex`` as input (:issue:`6439`)
 - Bug in ``str.extract`` when passed a non-default index (:issue:`6348`)
 - Bug in ``str.split`` when passed ``pat=None`` and ``n=1`` (:issue:`6466`)
@@ -207,6 +207,7 @@ Bug Fixes
 - Bug in ``pd.read_stata`` which would use the wrong data types and missing values (:issue:`6327`)
 - Bug in ``DataFrame.to_stata`` that lead to data loss in certain cases, and could exported using the
   wrong data types and missing values (:issue:`6335`)
+- Inconsistent types in Timestamp addition/subtraction (:issue:`6543`)
 
 
 pandas 0.13.1

pandas/tseries/tests/test_tslib.py

@@ -7,6 +7,7 @@
 
 from pandas.core.api import Timestamp
 from pandas.tslib import period_asfreq, period_ordinal
+from pandas.tseries.index import date_range
 from pandas.tseries.frequencies import get_freq
 from pandas import _np_version_under1p7
 import pandas.util.testing as tm
@@ -302,10 +303,32 @@ def test_period_ordinal_business_day(self):
         # Tuesday
         self.assertEqual(11418, period_ordinal(2013, 10, 8, 0, 0, 0, 0, 0, get_freq('B')))
 
-class TestTomeStampOps(tm.TestCase):
+class TestTimestampOps(tm.TestCase):
     def test_timestamp_and_datetime(self):
-        self.assertEqual((Timestamp(datetime.datetime(2013, 10,13)) - datetime.datetime(2013, 10,12)).days, 1)
-        self.assertEqual((datetime.datetime(2013, 10, 12) - Timestamp(datetime.datetime(2013, 10,13))).days, -1)
+        self.assertEqual((Timestamp(datetime.datetime(2013, 10, 13)) - datetime.datetime(2013, 10, 12)).days, 1)
+        self.assertEqual((datetime.datetime(2013, 10, 12) - Timestamp(datetime.datetime(2013, 10, 13))).days, -1)
+
+    def test_addition_subtraction_types(self):
+        # Assert on the types resulting from Timestamp +/- various date/time objects
+        datetime_instance = datetime.datetime(2014, 3, 4)
+        timedelta_instance = datetime.timedelta(seconds=1)
+        # build a timestamp with a frequency, since then it supports addition/subtraction of integers
+        timestamp_instance = date_range(datetime_instance, periods=1, freq='D')[0]
+
+        self.assertEqual(type(timestamp_instance + 1), Timestamp)
+        self.assertEqual(type(timestamp_instance - 1), Timestamp)
+
+        # Timestamp + datetime not supported, though subtraction is supported and yields timedelta
+        self.assertEqual(type(timestamp_instance - datetime_instance), datetime.timedelta)
+
+        self.assertEqual(type(timestamp_instance + timedelta_instance), Timestamp)
+        self.assertEqual(type(timestamp_instance - timedelta_instance), Timestamp)
+
+        if not _np_version_under1p7:
+            # Timestamp +/- datetime64 not supported, so not tested (could possibly assert error raised?)
+            timedelta64_instance = np.timedelta64(1, 'D')
+            self.assertEqual(type(timestamp_instance + timedelta64_instance), Timestamp)
+            self.assertEqual(type(timestamp_instance - timedelta64_instance), Timestamp)
 
 if __name__ == '__main__':
     nose.runmodule(argv=[__file__, '-vvs', '-x', '--pdb', '--pdb-failure'],

pandas/tslib.pyx

@@ -700,11 +700,11 @@ cdef class _Timestamp(datetime):
         return result
 
     def __sub__(self, other):
-        if is_integer_object(other):
-            neg_other = -other
-            return self + neg_other
-        # This calling convention is required
-        return datetime.__sub__(self, other)
+        if isinstance(other, datetime):
+            return datetime.__sub__(self, other)
+
+        neg_other = -other
+        return self + neg_other
 
     cpdef _get_field(self, field):
         out = get_date_field(np.array([self.value], dtype=np.int64), field)