Datetimelike add/sub catch cases more explicitly, tests (pandas-dev#19912)

Author: jbrockmendel

pandas/core/indexes/datetimelike.py

@@ -37,7 +37,7 @@
     is_period_dtype,
     is_timedelta64_dtype)
 from pandas.core.dtypes.generic import (
-    ABCIndex, ABCSeries, ABCPeriodIndex, ABCIndexClass)
+    ABCIndex, ABCSeries, ABCDataFrame, ABCPeriodIndex, ABCIndexClass)
 from pandas.core.dtypes.missing import isna
 from pandas.core import common as com, algorithms, ops
 from pandas.core.algorithms import checked_add_with_arr
@@ -48,6 +48,7 @@
 from pandas.util._decorators import Appender, cache_readonly
 import pandas.core.dtypes.concat as _concat
 import pandas.tseries.frequencies as frequencies
+from pandas.tseries.offsets import Tick, DateOffset
 
 import pandas.core.indexes.base as ibase
 _index_doc_kwargs = dict(ibase._index_doc_kwargs)
@@ -666,6 +667,9 @@ def _sub_nat(self):
     def _sub_period(self, other):
         return NotImplemented
 
+    def _add_offset(self, offset):
+        raise com.AbstractMethodError(self)
+
     def _addsub_offset_array(self, other, op):
         """
         Add or subtract array-like of DateOffset objects
@@ -705,14 +709,17 @@ def __add__(self, other):
             from pandas import DateOffset
 
             other = lib.item_from_zerodim(other)
-            if isinstance(other, ABCSeries):
+            if isinstance(other, (ABCSeries, ABCDataFrame)):
                 return NotImplemented
 
             # scalar others
             elif other is NaT:
                 result = self._add_nat()
-            elif isinstance(other, (DateOffset, timedelta, np.timedelta64)):
+            elif isinstance(other, (Tick, timedelta, np.timedelta64)):
                 result = self._add_delta(other)
+            elif isinstance(other, DateOffset):
+                # specifically _not_ a Tick
+                result = self._add_offset(other)
             elif isinstance(other, (datetime, np.datetime64)):
                 result = self._add_datelike(other)
             elif is_integer(other):
@@ -733,6 +740,12 @@ def __add__(self, other):
             elif is_integer_dtype(other) and self.freq is None:
                 # GH#19123
                 raise NullFrequencyError("Cannot shift with no freq")
+            elif is_float_dtype(other):
+                # Explicitly catch invalid dtypes
+                raise TypeError("cannot add {dtype}-dtype to {cls}"
+                                .format(dtype=other.dtype,
+                                        cls=type(self).__name__))
+
             else:  # pragma: no cover
                 return NotImplemented
 
@@ -753,17 +766,20 @@ def __radd__(self, other):
         cls.__radd__ = __radd__
 
         def __sub__(self, other):
-            from pandas import Index, DateOffset
+            from pandas import Index
 
             other = lib.item_from_zerodim(other)
-            if isinstance(other, ABCSeries):
+            if isinstance(other, (ABCSeries, ABCDataFrame)):
                 return NotImplemented
 
             # scalar others
             elif other is NaT:
                 result = self._sub_nat()
-            elif isinstance(other, (DateOffset, timedelta, np.timedelta64)):
+            elif isinstance(other, (Tick, timedelta, np.timedelta64)):
                 result = self._add_delta(-other)
+            elif isinstance(other, DateOffset):
+                # specifically _not_ a Tick
+                result = self._add_offset(-other)
             elif isinstance(other, (datetime, np.datetime64)):
                 result = self._sub_datelike(other)
             elif is_integer(other):
@@ -790,6 +806,12 @@ def __sub__(self, other):
             elif is_integer_dtype(other) and self.freq is None:
                 # GH#19123
                 raise NullFrequencyError("Cannot shift with no freq")
+
+            elif is_float_dtype(other):
+                # Explicitly catch invalid dtypes
+                raise TypeError("cannot subtract {dtype}-dtype from {cls}"
+                                .format(dtype=other.dtype,
+                                        cls=type(self).__name__))
             else:  # pragma: no cover
                 return NotImplemented
 

pandas/core/indexes/datetimes.py

@@ -932,8 +932,6 @@ def _add_delta(self, delta):
             if not isinstance(delta, TimedeltaIndex):
                 delta = TimedeltaIndex(delta)
             new_values = self._add_delta_tdi(delta)
-        elif isinstance(delta, DateOffset):
-            new_values = self._add_offset(delta).asi8
         else:
             new_values = self.astype('O') + delta
 
@@ -944,6 +942,7 @@ def _add_delta(self, delta):
         return result
 
     def _add_offset(self, offset):
+        assert not isinstance(offset, Tick)
         try:
             if self.tz is not None:
                 values = self.tz_localize(None)
@@ -952,12 +951,13 @@ def _add_offset(self, offset):
             result = offset.apply_index(values)
             if self.tz is not None:
                 result = result.tz_localize(self.tz)
-            return result
 
         except NotImplementedError:
             warnings.warn("Non-vectorized DateOffset being applied to Series "
                           "or DatetimeIndex", PerformanceWarning)
-            return self.astype('O') + offset
+            result = self.astype('O') + offset
+
+        return DatetimeIndex(result, freq='infer')
 
     def _format_native_types(self, na_rep='NaT', date_format=None, **kwargs):
         from pandas.io.formats.format import _get_format_datetime64_from_values

pandas/core/indexes/period.py

@@ -21,10 +21,11 @@
 
 import pandas.tseries.frequencies as frequencies
 from pandas.tseries.frequencies import get_freq_code as _gfc
+from pandas.tseries.offsets import Tick, DateOffset
+
 from pandas.core.indexes.datetimes import DatetimeIndex, Int64Index, Index
 from pandas.core.indexes.datetimelike import DatelikeOps, DatetimeIndexOpsMixin
 from pandas.core.tools.datetimes import parse_time_string
-import pandas.tseries.offsets as offsets
 
 from pandas._libs.lib import infer_dtype
 from pandas._libs import tslib, index as libindex
@@ -680,9 +681,9 @@ def to_timestamp(self, freq=None, how='start'):
 
     def _maybe_convert_timedelta(self, other):
         if isinstance(
-                other, (timedelta, np.timedelta64, offsets.Tick, np.ndarray)):
+                other, (timedelta, np.timedelta64, Tick, np.ndarray)):
             offset = frequencies.to_offset(self.freq.rule_code)
-            if isinstance(offset, offsets.Tick):
+            if isinstance(offset, Tick):
                 if isinstance(other, np.ndarray):
                     nanos = np.vectorize(delta_to_nanoseconds)(other)
                 else:
@@ -691,7 +692,7 @@ def _maybe_convert_timedelta(self, other):
                 check = np.all(nanos % offset_nanos == 0)
                 if check:
                     return nanos // offset_nanos
-        elif isinstance(other, offsets.DateOffset):
+        elif isinstance(other, DateOffset):
             freqstr = other.rule_code
             base = frequencies.get_base_alias(freqstr)
             if base == self.freq.rule_code:
@@ -707,6 +708,30 @@ def _maybe_convert_timedelta(self, other):
         msg = "Input has different freq from PeriodIndex(freq={0})"
         raise IncompatibleFrequency(msg.format(self.freqstr))
 
+    def _add_offset(self, other):
+        assert not isinstance(other, Tick)
+        base = frequencies.get_base_alias(other.rule_code)
+        if base != self.freq.rule_code:
+            msg = _DIFFERENT_FREQ_INDEX.format(self.freqstr, other.freqstr)
+            raise IncompatibleFrequency(msg)
+        return self.shift(other.n)
+
+    def _add_delta_td(self, other):
+        assert isinstance(other, (timedelta, np.timedelta64, Tick))
+        nanos = delta_to_nanoseconds(other)
+        own_offset = frequencies.to_offset(self.freq.rule_code)
+
+        if isinstance(own_offset, Tick):
+            offset_nanos = delta_to_nanoseconds(own_offset)
+            if np.all(nanos % offset_nanos == 0):
+                return self.shift(nanos // offset_nanos)
+
+        # raise when input doesn't have freq
+        raise IncompatibleFrequency("Input has different freq from "
+                                    "{cls}(freq={freqstr})"
+                                    .format(cls=type(self).__name__,
+                                            freqstr=self.freqstr))
+
     def _add_delta(self, other):
         ordinal_delta = self._maybe_convert_timedelta(other)
         return self.shift(ordinal_delta)

pandas/core/indexes/timedeltas.py

@@ -353,6 +353,12 @@ def _maybe_update_attributes(self, attrs):
             attrs['freq'] = 'infer'
         return attrs
 
+    def _add_offset(self, other):
+        assert not isinstance(other, Tick)
+        raise TypeError("cannot add the type {typ} to a {cls}"
+                        .format(typ=type(other).__name__,
+                                cls=type(self).__name__))
+
     def _add_delta(self, delta):
         """
         Add a timedelta-like, Tick, or TimedeltaIndex-like object

pandas/tests/indexes/datetimes/test_arithmetic.py

@@ -14,6 +14,7 @@
 from pandas import (Timestamp, Timedelta, Series,
                     DatetimeIndex, TimedeltaIndex,
                     date_range)
+from pandas.core import ops
 from pandas._libs import tslib
 from pandas._libs.tslibs.offsets import shift_months
 
@@ -307,6 +308,17 @@ def test_dti_cmp_list(self):
 
 class TestDatetimeIndexArithmetic(object):
 
+    # -------------------------------------------------------------
+    # Invalid Operations
+
+    @pytest.mark.parametrize('other', [3.14, np.array([2.0, 3.0])])
+    @pytest.mark.parametrize('op', [operator.add, ops.radd,
+                                    operator.sub, ops.rsub])
+    def test_dti_add_sub_float(self, op, other):
+        dti = DatetimeIndex(['2011-01-01', '2011-01-02'], freq='D')
+        with pytest.raises(TypeError):
+            op(dti, other)
+
     def test_dti_add_timestamp_raises(self):
         idx = DatetimeIndex(['2011-01-01', '2011-01-02'])
         msg = "cannot add DatetimeIndex and Timestamp"

pandas/tests/indexes/period/test_arithmetic.py

@@ -1,5 +1,7 @@
 # -*- coding: utf-8 -*-
 from datetime import timedelta
+import operator
+
 import pytest
 import numpy as np
 
@@ -9,6 +11,7 @@
                     period_range, Period, PeriodIndex,
                     _np_version_under1p10)
 import pandas.core.indexes.period as period
+from pandas.core import ops
 from pandas.errors import PerformanceWarning
 
 
@@ -256,6 +259,18 @@ def test_comp_nat(self, dtype):
 
 class TestPeriodIndexArithmetic(object):
 
+    # -------------------------------------------------------------
+    # Invalid Operations
+
+    @pytest.mark.parametrize('other', [3.14, np.array([2.0, 3.0])])
+    @pytest.mark.parametrize('op', [operator.add, ops.radd,
+                                    operator.sub, ops.rsub])
+    def test_pi_add_sub_float(self, op, other):
+        dti = pd.DatetimeIndex(['2011-01-01', '2011-01-02'], freq='D')
+        pi = dti.to_period('D')
+        with pytest.raises(TypeError):
+            op(pi, other)
+
     # -----------------------------------------------------------------
     # __add__/__sub__ with ndarray[datetime64] and ndarray[timedelta64]
 

pandas/tests/indexes/timedeltas/test_arithmetic.py

@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+import operator
+
 import pytest
 import numpy as np
 from datetime import timedelta
@@ -11,6 +13,7 @@
                     Series,
                     Timestamp, Timedelta)
 from pandas.errors import PerformanceWarning, NullFrequencyError
+from pandas.core import ops
 
 
 @pytest.fixture(params=[pd.offsets.Hour(2), timedelta(hours=2),
@@ -270,6 +273,15 @@ class TestTimedeltaIndexArithmetic(object):
     # -------------------------------------------------------------
     # Invalid Operations
 
+    @pytest.mark.parametrize('other', [3.14, np.array([2.0, 3.0])])
+    @pytest.mark.parametrize('op', [operator.add, ops.radd,
+                                    operator.sub, ops.rsub])
+    def test_tdi_add_sub_float(self, op, other):
+        dti = DatetimeIndex(['2011-01-01', '2011-01-02'], freq='D')
+        tdi = dti - dti.shift(1)
+        with pytest.raises(TypeError):
+            op(tdi, other)
+
     def test_tdi_add_str_invalid(self):
         # GH 13624
         tdi = TimedeltaIndex(['1 day', '2 days'])