dispatch Series[datetime64] comparison ops to DatetimeIndex (pandas-dev#19800)

Author: jbrockmendel

pandas/core/indexes/datetimes.py

@@ -138,11 +138,9 @@ def wrapper(self, other):
             result = func(np.asarray(other))
             result = com._values_from_object(result)
 
-            if isinstance(other, Index):
-                o_mask = other.values.view('i8') == libts.iNaT
-            else:
-                o_mask = other.view('i8') == libts.iNaT
-
+            # Make sure to pass an array to result[...]; indexing with
+            # Series breaks with older version of numpy
+            o_mask = np.array(isna(other))
             if o_mask.any():
                 result[o_mask] = nat_result
 

pandas/core/ops.py

@@ -10,8 +10,7 @@
 import numpy as np
 import pandas as pd
 
-from pandas._libs import (lib, index as libindex,
-                          algos as libalgos, ops as libops)
+from pandas._libs import algos as libalgos, ops as libops
 
 from pandas import compat
 from pandas.util._decorators import Appender
@@ -1127,24 +1126,20 @@ def na_op(x, y):
             # integer comparisons
 
             # we have a datetime/timedelta and may need to convert
+            assert not needs_i8_conversion(x)
             mask = None
-            if (needs_i8_conversion(x) or
-                    (not is_scalar(y) and needs_i8_conversion(y))):
-
-                if is_scalar(y):
-                    mask = isna(x)
-                    y = libindex.convert_scalar(x, com._values_from_object(y))
-                else:
-                    mask = isna(x) | isna(y)
-                    y = y.view('i8')
+            if not is_scalar(y) and needs_i8_conversion(y):
+                mask = isna(x) | isna(y)
+                y = y.view('i8')
                 x = x.view('i8')
 
-            try:
+            method = getattr(x, name, None)
+            if method is not None:
                 with np.errstate(all='ignore'):
-                    result = getattr(x, name)(y)
+                    result = method(y)
                 if result is NotImplemented:
                     raise TypeError("invalid type comparison")
-            except AttributeError:
+            else:
                 result = op(x, y)
 
             if mask is not None and mask.any():
@@ -1174,6 +1169,14 @@ def wrapper(self, other, axis=None):
             return self._constructor(res_values, index=self.index,
                                      name=res_name)
 
+        if is_datetime64_dtype(self) or is_datetime64tz_dtype(self):
+            # Dispatch to DatetimeIndex to ensure identical
+            # Series/Index behavior
+            res_values = dispatch_to_index_op(op, self, other,
+                                              pd.DatetimeIndex)
+            return self._constructor(res_values, index=self.index,
+                                     name=res_name)
+
         elif is_timedelta64_dtype(self):
             res_values = dispatch_to_index_op(op, self, other,
                                               pd.TimedeltaIndex)
@@ -1191,8 +1194,7 @@ def wrapper(self, other, axis=None):
         elif isinstance(other, (np.ndarray, pd.Index)):
             # do not check length of zerodim array
             # as it will broadcast
-            if (not is_scalar(lib.item_from_zerodim(other)) and
-                    len(self) != len(other)):
+            if other.ndim != 0 and len(self) != len(other):
                 raise ValueError('Lengths must match to compare')
 
             res_values = na_op(self.values, np.asarray(other))

pandas/tests/indexes/datetimes/test_partial_slicing.py

@@ -2,7 +2,7 @@
 
 import pytest
 
-from datetime import datetime, date
+from datetime import datetime
 import numpy as np
 import pandas as pd
 import operator as op
@@ -349,7 +349,7 @@ def test_loc_datetime_length_one(self):
 
     @pytest.mark.parametrize('datetimelike', [
         Timestamp('20130101'), datetime(2013, 1, 1),
-        date(2013, 1, 1), np.datetime64('2013-01-01T00:00', 'ns')])
+        np.datetime64('2013-01-01T00:00', 'ns')])
     @pytest.mark.parametrize('op,expected', [
         (op.lt, [True, False, False, False]),
         (op.le, [True, True, False, False]),

pandas/tests/series/test_arithmetic.py

@@ -88,6 +88,23 @@ def test_ser_cmp_result_names(self, names, op):
 
 
 class TestTimestampSeriesComparison(object):
+    def test_dt64ser_cmp_date_invalid(self):
+        # GH#19800 datetime.date comparison raises to
+        # match DatetimeIndex/Timestamp.  This also matches the behavior
+        # of stdlib datetime.datetime
+        ser = pd.Series(pd.date_range('20010101', periods=10), name='dates')
+        date = ser.iloc[0].to_pydatetime().date()
+        assert not (ser == date).any()
+        assert (ser != date).all()
+        with pytest.raises(TypeError):
+            ser > date
+        with pytest.raises(TypeError):
+            ser < date
+        with pytest.raises(TypeError):
+            ser >= date
+        with pytest.raises(TypeError):
+            ser <= date
+
     def test_dt64ser_cmp_period_scalar(self):
         ser = Series(pd.period_range('2000-01-01', periods=10, freq='D'))
         val = Period('2000-01-04', freq='D')

pandas/tests/test_base.py

@@ -10,7 +10,7 @@
 import pandas as pd
 import pandas.compat as compat
 from pandas.core.dtypes.common import (
-    is_object_dtype, is_datetimetz,
+    is_object_dtype, is_datetimetz, is_datetime64_dtype,
     needs_i8_conversion)
 import pandas.util.testing as tm
 from pandas import (Series, Index, DatetimeIndex, TimedeltaIndex,
@@ -296,14 +296,21 @@ def test_none_comparison(self):
                 # result = None != o  # noqa
                 # assert result.iat[0]
                 # assert result.iat[1]
+                if (is_datetime64_dtype(o) or is_datetimetz(o)):
+                    # Following DatetimeIndex (and Timestamp) convention,
+                    # inequality comparisons with Series[datetime64] raise
+                    with pytest.raises(TypeError):
+                        None > o
+                    with pytest.raises(TypeError):
+                        o > None
+                else:
+                    result = None > o
+                    assert not result.iat[0]
+                    assert not result.iat[1]
 
-                result = None > o
-                assert not result.iat[0]
-                assert not result.iat[1]
-
-                result = o < None
-                assert not result.iat[0]
-                assert not result.iat[1]
+                    result = o < None
+                    assert not result.iat[0]
+                    assert not result.iat[1]
 
     def test_ndarray_compat_properties(self):