BUG: GH11349 where Series.apply and Series.map did not box timedelta64

doc/source/whatsnew/v0.18.0.txt

@@ -167,6 +167,64 @@ Backwards incompatible API changes
 - The parameter ``out`` has been removed from the ``Series.round()`` method. (:issue:`11763`)
 - ``DataFrame.round()`` leaves non-numeric columns unchanged in its return, rather than raises. (:issue:`11885`)
 
+NaT and Timedelta operations
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+``NaT`` and ``Timedelta`` have expanded arithmetic operations, which are extended to ``Series``
+arithmetic where applicable.  Operations defined for ``datetime64[ns]`` or ``timedelta64[ns]``
+are now also defined for ``NaT`` (:issue:`11564`).
+
+``NaT`` now supports arithmetic operations with integers and floats.
+
+.. ipython:: python
+
+   pd.NaT * 1
+   pd.NaT * 1.5
+   pd.NaT / 2
+   pd.NaT * np.nan
+
+``NaT`` defines more arithmetic operations with ``datetime64[ns]`` and ``timedelta64[ns]``.
+
+.. ipython:: python
+
+   pd.NaT / pd.NaT
+   pd.Timedelta('1s') / pd.NaT
+
+``NaT`` may represent either a ``datetime64[ns]`` null or a ``timedelta64[ns]`` null.
+Given the ambiguity, it is treated as a `timedelta64[ns]`, which allows more operations
+to succeed.
+
+.. ipython:: python
+   :okexcept:
+
+   pd.NaT + pd.NaT
+   # same as
+   pd.Timedelta('1s') + pd.Timedelta('1s')
+   # as opposed to
+   pd.Timestamp('1990315') + pd.Timestamp('19900315')
+
+However, when wrapped in a ``Series`` whose ``dtype`` is ``datetime64[ns]`` or ``timedelta64[ns]``,
+the ``dtype`` information is respected.
+
+.. ipython:: python
+
+   pd.Series([pd.NaT], dtype='<M8[ns]') + pd.Series([pd.NaT], dtype='<M8[ns]')
+   pd.Series([pd.NaT], dtype='<m8[ns]') + pd.Series([pd.NaT], dtype='<m8[ns]')
+
+``Timedelta`` division by ``float``s now works.
+
+.. ipython:: python
+
+   pd.Timedelta('1s') / 2.0
+
+Subtraction by ``Timedelta`` in a ``Series`` by a ``Timestamp`` works (:issue:`11925`)
+
+.. ipython:: python
+
+   ser = pd.Series(pd.timedelta_range('1 day', periods=3))
+   ser
+   pd.Timestamp('2012-01-01') - ser
+
 Bug in QuarterBegin with n=0
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -312,6 +370,7 @@ Bug Fixes
 - Bug in ``DataFrame.info`` when duplicated column names exist (:issue:`11761`)
 - Bug in ``.copy`` of datetime tz-aware objects (:issue:`11794`)
 
+- Bug in ``Series.apply`` and ``Series.map`` where ``timedelta64`` was not boxed (:issue:`11349`)
 
 
 

pandas/core/ops.py

@@ -291,6 +291,7 @@ def __init__(self, left, right, name, na_op):
         self.is_datetime64tz_lhs = is_datetime64tz_dtype(lvalues)
         self.is_datetime_lhs = self.is_datetime64_lhs or self.is_datetime64tz_lhs
         self.is_integer_lhs = left.dtype.kind in ['i', 'u']
+        self.is_floating_lhs = left.dtype.kind == 'f'
 
         # right
         self.right = right
@@ -300,32 +301,25 @@ def __init__(self, left, right, name, na_op):
         self.is_datetime_rhs = self.is_datetime64_rhs or self.is_datetime64tz_rhs
         self.is_timedelta_rhs = is_timedelta64_dtype(rvalues)
         self.is_integer_rhs = rvalues.dtype.kind in ('i', 'u')
+        self.is_floating_rhs = rvalues.dtype.kind == 'f'
 
         self._validate(lvalues, rvalues, name)
         self.lvalues, self.rvalues = self._convert_for_datetime(lvalues, rvalues)
 
     def _validate(self, lvalues, rvalues, name):
         # timedelta and integer mul/div
 
-        if (self.is_timedelta_lhs and self.is_integer_rhs) or (
-            self.is_integer_lhs and self.is_timedelta_rhs):
+        if (self.is_timedelta_lhs and
+                (self.is_integer_rhs or self.is_floating_rhs)) or (
+            self.is_timedelta_rhs and
+                    (self.is_integer_lhs or self.is_floating_lhs)):
 
-            if name not in ('__div__', '__truediv__', '__mul__'):
+            if name not in ('__div__', '__truediv__', '__mul__', '__rmul__'):
                 raise TypeError("can only operate on a timedelta and an "
-                                "integer for division, but the operator [%s]"
-                                "was passed" % name)
+                                "integer or a float for division and "
+                                "multiplication, but the operator [%s] was"
+                                "passed" % name)
 
-        # 2 datetimes
-        elif self.is_datetime_lhs and self.is_datetime_rhs:
-
-            if name not in ('__sub__','__rsub__'):
-                raise TypeError("can only operate on a datetimes for"
-                                " subtraction, but the operator [%s] was"
-                                " passed" % name)
-
-            # if tz's must be equal (same or None)
-            if getattr(lvalues,'tz',None) != getattr(rvalues,'tz',None):
-                raise ValueError("Incompatbile tz's on datetime subtraction ops")
 
         # 2 timedeltas
         elif ((self.is_timedelta_lhs and
@@ -339,6 +333,7 @@ def _validate(self, lvalues, rvalues, name):
                                 "addition, subtraction, and division, but the"
                                 " operator [%s] was passed" % name)
 
+
         # datetime and timedelta/DateOffset
         elif (self.is_datetime_lhs and
               (self.is_timedelta_rhs or self.is_offset_rhs)):
@@ -349,6 +344,28 @@ def _validate(self, lvalues, rvalues, name):
                                 " but the operator [%s] was passed" %
                                 name)
 
+        elif (self.is_datetime_rhs and
+              (self.is_timedelta_lhs or self.is_offset_lhs)):
+            if name not in ('__add__', '__radd__', '__rsub__'):
+                raise TypeError("can only operate on a timedelta/DateOffset with a rhs of"
+                                " a datetime for addition,"
+                                " but the operator [%s] was passed" %
+                                name)
+
+
+        # 2 datetimes
+        elif self.is_datetime_lhs and self.is_datetime_rhs:
+
+            if name not in ('__sub__','__rsub__'):
+                raise TypeError("can only operate on a datetimes for"
+                                " subtraction, but the operator [%s] was"
+                                " passed" % name)
+
+            # if tz's must be equal (same or None)
+            if getattr(lvalues,'tz',None) != getattr(rvalues,'tz',None):
+                raise ValueError("Incompatbile tz's on datetime subtraction ops")
+
+
         elif ((self.is_timedelta_lhs or self.is_offset_lhs)
               and self.is_datetime_rhs):
 
@@ -357,7 +374,7 @@ def _validate(self, lvalues, rvalues, name):
                                 " a datetime for addition, but the operator"
                                 " [%s] was passed" % name)
         else:
-            raise TypeError('cannot operate on a series with out a rhs '
+            raise TypeError('cannot operate on a series without a rhs '
                             'of a series/ndarray of type datetime64[ns] '
                             'or a timedelta')
 
@@ -366,17 +383,25 @@ def _convert_to_array(self, values, name=None, other=None):
         from pandas.tseries.timedeltas import to_timedelta
 
         ovalues = values
+        supplied_dtype = None
         if not is_list_like(values):
             values = np.array([values])
-
-        inferred_type = lib.infer_dtype(values)
-
-        if inferred_type in ('datetime64', 'datetime', 'date', 'time'):
+        # if this is a Series that contains relevant dtype info, then use this
+        # instead of the inferred type; this avoids coercing Series([NaT],
+        # dtype='datetime64[ns]') to Series([NaT], dtype='timedelta64[ns]')
+        elif isinstance(values, pd.Series) and (
+                    is_timedelta64_dtype(values) or is_datetime64_dtype(values)):
+            supplied_dtype = values.dtype
+        inferred_type = supplied_dtype or lib.infer_dtype(values)
+        if (inferred_type in ('datetime64', 'datetime', 'date', 'time')
+            or com.is_datetimetz(inferred_type)):
             # if we have a other of timedelta, but use pd.NaT here we
             # we are in the wrong path
-            if (other is not None and other.dtype == 'timedelta64[ns]' and
-                    all(isnull(v) for v in values)):
-                values = np.empty(values.shape, dtype=other.dtype)
+            if (supplied_dtype is None
+                and other is not None
+                and (other.dtype in ('timedelta64[ns]', 'datetime64[ns]'))
+                and isnull(values).all()):
+                values = np.empty(values.shape, dtype='timedelta64[ns]')
                 values[:] = iNaT
 
             # a datelike
@@ -401,18 +426,15 @@ def _convert_to_array(self, values, name=None, other=None):
                 values = values.astype('timedelta64[ns]')
             elif isinstance(values, pd.PeriodIndex):
                 values = values.to_timestamp().to_series()
-            elif name not in ('__truediv__', '__div__', '__mul__'):
+            elif name not in ('__truediv__', '__div__', '__mul__', '__rmul__'):
                 raise TypeError("incompatible type for a datetime/timedelta "
                                 "operation [{0}]".format(name))
         elif inferred_type == 'floating':
-            # all nan, so ok, use the other dtype (e.g. timedelta or datetime)
-            if isnull(values).all():
+            if isnull(values).all() and name in ('__add__', '__radd__',
+                                                 '__sub__', '__rsub__'):
                 values = np.empty(values.shape, dtype=other.dtype)
                 values[:] = iNaT
-            else:
-                raise TypeError(
-                    'incompatible type [{0}] for a datetime/timedelta '
-                    'operation'.format(np.array(values).dtype))
+            return values
         elif self._is_offset(values):
             return values
         else:
@@ -431,7 +453,10 @@ def _convert_for_datetime(self, lvalues, rvalues):
 
             # datetime subtraction means timedelta
             if self.is_datetime_lhs and self.is_datetime_rhs:
-                self.dtype = 'timedelta64[ns]'
+                if self.name in ('__sub__', '__rsub__'):
+                    self.dtype = 'timedelta64[ns]'
+                else:
+                    self.dtype = 'datetime64[ns]'
             elif self.is_datetime64tz_lhs:
                 self.dtype = lvalues.dtype
             elif self.is_datetime64tz_rhs:
@@ -482,7 +507,8 @@ def _offset(lvalues, rvalues):
                 rvalues = to_timedelta(rvalues)
 
             lvalues = lvalues.astype(np.int64)
-            rvalues = rvalues.astype(np.int64)
+            if not self.is_floating_rhs:
+                rvalues = rvalues.astype(np.int64)
 
             # time delta division -> unit less
             # integer gets converted to timedelta in np < 1.6
@@ -580,7 +606,7 @@ def wrapper(left, right, name=name, na_op=na_op):
             lvalues, rvalues = left, right
             dtype = None
             wrap_results = lambda x: x
-        elif time_converted == NotImplemented:
+        elif time_converted is NotImplemented:
             return NotImplemented
         else:
             left, right = time_converted.left, time_converted.right

pandas/core/series.py

@@ -2078,8 +2078,9 @@ def map(self, arg, na_action=None):
             same index as caller
         """
         values = self._values
-        if com.is_datetime64_dtype(values.dtype):
-            values = lib.map_infer(values, lib.Timestamp)
+        if needs_i8_conversion(values.dtype):
+            boxer = i8_boxer(values)
+            values = lib.map_infer(values, boxer)
 
         if na_action == 'ignore':
             mask = isnull(values)
@@ -2210,8 +2211,9 @@ def apply(self, func, convert_dtype=True, args=(), **kwds):
             return f(self)
 
         values = _values_from_object(self)
-        if com.is_datetime64_dtype(values.dtype):
-            values = lib.map_infer(values, lib.Timestamp)
+        if needs_i8_conversion(values.dtype):
+            boxer = i8_boxer(values)
+            values = lib.map_infer(values, boxer)
 
         mapped = lib.map_infer(values, f, convert=convert_dtype)
         if len(mapped) and isinstance(mapped[0], Series):