BUG: Bug in Timestamp-Timestamp not returning a Timedelta type and datelike-datelike ops with timezones (GH8865)

Author: jreback

doc/source/whatsnew/v0.15.2.txt

@@ -92,6 +92,24 @@ Experimental
 
 Bug Fixes
 ~~~~~~~~~
+
+- Bug in Timestamp-Timestamp not returning a Timedelta type and datelike-datelike ops with timezones (:issue:`8865`)
+- Made consistent a timezone mismatch exception (either tz operated with None or incompatible timezone), will now return ``TypeError`` rather than ``ValueError`` (a couple of edge cases only), (:issue:`8865`)
+- Report a ``TypeError`` when invalid/no paramaters are passed in a groupby (:issue:`8015`)
+- Bug in packaging pandas with ``py2app/cx_Freeze`` (:issue:`8602`, :issue:`8831`)
+- Bug in ``groupby`` signatures that didn't include \*args or \*\*kwargs (:issue:`8733`).
+- ``io.data.Options`` now raises ``RemoteDataError`` when no expiry dates are available from Yahoo and when it receives no data from Yahoo (:issue:`8761`), (:issue:`8783`).
+- Unclear error message in csv parsing when passing dtype and names and the parsed data is a different data type (:issue:`8833`)
+- Bug in slicing a multi-index with an empty list and at least one boolean indexer (:issue:`8781`)
+- ``io.data.Options`` now raises ``RemoteDataError`` when no expiry dates are available from Yahoo (:issue:`8761`).
+- ``Timedelta`` kwargs may now be numpy ints and floats (:issue:`8757`).
+- Fixed several outstanding bugs for ``Timedelta`` arithmetic and comparisons (:issue:`8813`, :issue:`5963`, :issue:`5436`).
+- ``sql_schema`` now generates dialect appropriate ``CREATE TABLE`` statements (:issue:`8697`)
+- ``slice`` string method now takes step into account (:issue:`8754`)
+- Bug in ``BlockManager`` where setting values with different type would break block integrity (:issue:`8850`)
+- Bug in ``DatetimeIndex`` when using ``time`` object as key (:issue:`8667`)
+- Bug in ``merge`` where ``how='left'`` and ``sort=False`` would not preserve left frame order (:issue:`7331`)
+
 - Fix negative step support for label-based slices (:issue:`8753`)
 
   Old behavior:

pandas/tests/test_base.py

@@ -285,8 +285,8 @@ def test_ops(self):
                     expected = pd.Period(ordinal=getattr(o.values, op)(), freq=o.freq)
                 try:
                     self.assertEqual(result, expected)
-                except ValueError:
-                    # comparing tz-aware series with np.array results in ValueError
+                except TypeError:
+                    # comparing tz-aware series with np.array results in TypeError
                     expected = expected.astype('M8[ns]').astype('int64')
                     self.assertEqual(result.value, expected)
 

pandas/tseries/base.py

@@ -346,7 +346,7 @@ def __sub__(self, other):
         cls.__sub__ = __sub__
 
         def __rsub__(self, other):
-            return -self + other
+            return -(self - other)
         cls.__rsub__ = __rsub__
 
         cls.__iadd__ = __add__

pandas/tseries/index.py

@@ -381,7 +381,7 @@ def _generate(cls, start, end, periods, name, offset,
         try:
             inferred_tz = tools._infer_tzinfo(start, end)
         except:
-            raise ValueError('Start and end cannot both be tz-aware with '
+            raise TypeError('Start and end cannot both be tz-aware with '
                              'different timezones')
 
         inferred_tz = tslib.maybe_get_tz(inferred_tz)
@@ -645,6 +645,11 @@ def _sub_datelike(self, other):
 
         from pandas import TimedeltaIndex
         other = Timestamp(other)
+
+        # require tz compat
+        if tslib.get_timezone(self.tz) != tslib.get_timezone(other.tzinfo):
+            raise TypeError("Timestamp subtraction must have the same timezones or no timezones")
+
         i8 = self.asi8
         result = i8 - other.value
         result = self._maybe_mask_results(result,fill_value=tslib.iNaT)

pandas/tseries/tests/test_base.py

@@ -468,6 +468,74 @@ def test_subtraction_ops(self):
         expected = DatetimeIndex(['20121231',pd.NaT,'20121230'])
         tm.assert_index_equal(result,expected)
 
+    def test_subtraction_ops_with_tz(self):
+
+        # check that dt/dti subtraction ops with tz are validated
+        dti = date_range('20130101',periods=3)
+        ts = Timestamp('20130101')
+        dt = ts.to_datetime()
+        dti_tz = date_range('20130101',periods=3).tz_localize('US/Eastern')
+        ts_tz = Timestamp('20130101').tz_localize('US/Eastern')
+        ts_tz2 = Timestamp('20130101').tz_localize('CET')
+        dt_tz = ts_tz.to_datetime()
+        td = Timedelta('1 days')
+
+        def _check(result, expected):
+            self.assertEqual(result,expected)
+            self.assertIsInstance(result, Timedelta)
+
+        # scalars
+        result = ts - ts
+        expected = Timedelta('0 days')
+        _check(result, expected)
+
+        result = dt_tz - ts_tz
+        expected = Timedelta('0 days')
+        _check(result, expected)
+
+        result = ts_tz - dt_tz
+        expected = Timedelta('0 days')
+        _check(result, expected)
+
+        # tz mismatches
+        self.assertRaises(TypeError, lambda : dt_tz - ts)
+        self.assertRaises(TypeError, lambda : dt_tz - dt)
+        self.assertRaises(TypeError, lambda : dt_tz - ts_tz2)
+        self.assertRaises(TypeError, lambda : dt - dt_tz)
+        self.assertRaises(TypeError, lambda : ts - dt_tz)
+        self.assertRaises(TypeError, lambda : ts_tz2 - ts)
+        self.assertRaises(TypeError, lambda : ts_tz2 - dt)
+        self.assertRaises(TypeError, lambda : ts_tz - ts_tz2)
+
+        # with dti
+        self.assertRaises(TypeError, lambda : dti - ts_tz)
+        self.assertRaises(TypeError, lambda : dti_tz - ts)
+        self.assertRaises(TypeError, lambda : dti_tz - ts_tz2)
+
+        result = dti_tz-dt_tz
+        expected = TimedeltaIndex(['0 days','1 days','2 days'])
+        tm.assert_index_equal(result,expected)
+
+        result = dt_tz-dti_tz
+        expected = TimedeltaIndex(['0 days','-1 days','-2 days'])
+        tm.assert_index_equal(result,expected)
+
+        result = dti_tz-ts_tz
+        expected = TimedeltaIndex(['0 days','1 days','2 days'])
+        tm.assert_index_equal(result,expected)
+
+        result = ts_tz-dti_tz
+        expected = TimedeltaIndex(['0 days','-1 days','-2 days'])
+        tm.assert_index_equal(result,expected)
+
+        result = td - td
+        expected = Timedelta('0 days')
+        _check(result, expected)
+
+        result = dti_tz - td
+        expected = DatetimeIndex(['20121231','20130101','20130102'],tz='US/Eastern')
+        tm.assert_index_equal(result,expected)
+
     def test_dti_tdi_numeric_ops(self):
 
         # These are normally union/diff set-like ops

pandas/tseries/tests/test_tslib.py

@@ -5,7 +5,7 @@
 from pandas import tslib
 import datetime
 
-from pandas.core.api import Timestamp, Series
+from pandas.core.api import Timestamp, Series, Timedelta
 from pandas.tslib import period_asfreq, period_ordinal, get_timezone
 from pandas.tseries.index import date_range
 from pandas.tseries.frequencies import get_freq
@@ -232,13 +232,13 @@ def test_tz(self):
         conv = local.tz_convert('US/Eastern')
         self.assertEqual(conv.nanosecond, 5)
         self.assertEqual(conv.hour, 19)
-        
+
     def test_tz_localize_ambiguous(self):
-        
+
         ts = Timestamp('2014-11-02 01:00')
         ts_dst = ts.tz_localize('US/Eastern', ambiguous=True)
         ts_no_dst = ts.tz_localize('US/Eastern', ambiguous=False)
-        
+
         rng = date_range('2014-11-02', periods=3, freq='H', tz='US/Eastern')
         self.assertEqual(rng[1], ts_dst)
         self.assertEqual(rng[2], ts_no_dst)
@@ -679,8 +679,8 @@ def test_addition_subtraction_types(self):
         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)
-
+        # more tests in tseries/base/tests/test_base.py
+        self.assertEqual(type(timestamp_instance - datetime_instance), Timedelta)
         self.assertEqual(type(timestamp_instance + timedelta_instance), Timestamp)
         self.assertEqual(type(timestamp_instance - timedelta_instance), Timestamp)
 

pandas/tslib.pyx

@@ -810,10 +810,10 @@ cdef class _Timestamp(datetime):
                                         object other) except -1:
         if self.tzinfo is None:
             if other.tzinfo is not None:
-                raise ValueError('Cannot compare tz-naive and tz-aware '
+                raise TypeError('Cannot compare tz-naive and tz-aware '
                                  'timestamps')
         elif other.tzinfo is None:
-            raise ValueError('Cannot compare tz-naive and tz-aware timestamps')
+            raise TypeError('Cannot compare tz-naive and tz-aware timestamps')
 
     cpdef datetime to_datetime(_Timestamp self):
         cdef:
@@ -863,6 +863,11 @@ cdef class _Timestamp(datetime):
 
         # a Timestamp-DatetimeIndex -> yields a negative TimedeltaIndex
         elif getattr(other,'_typ',None) == 'datetimeindex':
+
+            # we may be passed reverse ops
+            if get_timezone(getattr(self,'tzinfo',None)) != get_timezone(other.tz):
+                    raise TypeError("Timestamp subtraction must have the same timezones or no timezones")
+
             return -other.__sub__(self)
 
         # a Timestamp-TimedeltaIndex -> yields a negative TimedeltaIndex
@@ -871,6 +876,23 @@ cdef class _Timestamp(datetime):
 
         elif other is NaT:
             return NaT
+
+        # coerce if necessary if we are a Timestamp-like
+        if isinstance(self, datetime) and (isinstance(other, datetime) or is_datetime64_object(other)):
+            self = Timestamp(self)
+            other = Timestamp(other)
+
+            # validate tz's
+            if get_timezone(self.tzinfo) != get_timezone(other.tzinfo):
+                raise TypeError("Timestamp subtraction must have the same timezones or no timezones")
+
+            # scalar Timestamp/datetime - Timestamp/datetime -> yields a Timedelta
+            try:
+                return Timedelta(self.value-other.value)
+            except (OverflowError, OutOfBoundsDatetime):
+                pass
+
+        # scalar Timestamp/datetime - Timedelta -> yields a Timestamp (with same timezone if specified)
         return datetime.__sub__(self, other)
 
     cpdef _get_field(self, field):