implement truediv, rtruediv directly in TimedeltaArray; tests (pandas-dev#23829)

Author: jbrockmendel

doc/source/whatsnew/v0.24.0.rst

@@ -1256,7 +1256,7 @@ Timedelta
 - Bug in :class:`TimedeltaIndex` where adding a timezone-aware datetime scalar incorrectly returned a timezone-naive :class:`DatetimeIndex` (:issue:`23215`)
 - Bug in :class:`TimedeltaIndex` where adding ``np.timedelta64('NaT')`` incorrectly returned an all-`NaT` :class:`DatetimeIndex` instead of an all-`NaT` :class:`TimedeltaIndex` (:issue:`23215`)
 - Bug in :class:`Timedelta` and :func:`to_timedelta()` have inconsistencies in supported unit string (:issue:`21762`)
-
+- Bug in :class:`TimedeltaIndex` division where dividing by another :class:`TimedeltaIndex` raised ``TypeError`` instead of returning a :class:`Float64Index` (:issue:`23829`, :issue:`22631`)
 
 Timezones
 ^^^^^^^^^

pandas/core/arrays/timedeltas.py

@@ -7,7 +7,7 @@
 
 import numpy as np
 
-from pandas._libs import algos, tslibs
+from pandas._libs import algos, lib, tslibs
 from pandas._libs.tslibs import NaT, Timedelta, Timestamp, iNaT
 from pandas._libs.tslibs.fields import get_timedelta_field
 from pandas._libs.tslibs.timedeltas import (
@@ -177,7 +177,7 @@ def __new__(cls, values, freq=None, dtype=_TD_DTYPE, copy=False):
                                          passed=freq.freqstr))
             elif freq is None:
                 freq = inferred_freq
-                freq_infer = False
+            freq_infer = False
 
         result = cls._simple_new(values, freq=freq)
         # check that we are matching freqs
@@ -355,12 +355,108 @@ def _evaluate_with_timedelta_like(self, other, op):
 
     __mul__ = _wrap_tdi_op(operator.mul)
     __rmul__ = __mul__
-    __truediv__ = _wrap_tdi_op(operator.truediv)
     __floordiv__ = _wrap_tdi_op(operator.floordiv)
     __rfloordiv__ = _wrap_tdi_op(ops.rfloordiv)
 
+    def __truediv__(self, other):
+        # timedelta / X is well-defined for timedelta-like or numeric X
+        other = lib.item_from_zerodim(other)
+
+        if isinstance(other, (ABCSeries, ABCDataFrame, ABCIndexClass)):
+            return NotImplemented
+
+        if isinstance(other, (timedelta, np.timedelta64, Tick)):
+            other = Timedelta(other)
+            if other is NaT:
+                # specifically timedelta64-NaT
+                result = np.empty(self.shape, dtype=np.float64)
+                result.fill(np.nan)
+                return result
+
+            # otherwise, dispatch to Timedelta implementation
+            return self._data / other
+
+        elif lib.is_scalar(other):
+            # assume it is numeric
+            result = self._data / other
+            freq = None
+            if self.freq is not None:
+                # Tick division is not implemented, so operate on Timedelta
+                freq = self.freq.delta / other
+            return type(self)(result, freq=freq)
+
+        if not hasattr(other, "dtype"):
+            # e.g. list, tuple
+            other = np.array(other)
+
+        if len(other) != len(self):
+            raise ValueError("Cannot divide vectors with unequal lengths")
+
+        elif is_timedelta64_dtype(other):
+            # let numpy handle it
+            return self._data / other
+
+        elif is_object_dtype(other):
+            # Note: we do not do type inference on the result, so either
+            #  an object array or numeric-dtyped (if numpy does inference)
+            #  will be returned.  GH#23829
+            result = [self[n] / other[n] for n in range(len(self))]
+            result = np.array(result)
+            return result
+
+        else:
+            result = self._data / other
+            return type(self)(result)
+
+    def __rtruediv__(self, other):
+        # X / timedelta is defined only for timedelta-like X
+        other = lib.item_from_zerodim(other)
+
+        if isinstance(other, (ABCSeries, ABCDataFrame, ABCIndexClass)):
+            return NotImplemented
+
+        if isinstance(other, (timedelta, np.timedelta64, Tick)):
+            other = Timedelta(other)
+            if other is NaT:
+                # specifically timedelta64-NaT
+                result = np.empty(self.shape, dtype=np.float64)
+                result.fill(np.nan)
+                return result
+
+            # otherwise, dispatch to Timedelta implementation
+            return other / self._data
+
+        elif lib.is_scalar(other):
+            raise TypeError("Cannot divide {typ} by {cls}"
+                            .format(typ=type(other).__name__,
+                                    cls=type(self).__name__))
+
+        if not hasattr(other, "dtype"):
+            # e.g. list, tuple
+            other = np.array(other)
+
+        if len(other) != len(self):
+            raise ValueError("Cannot divide vectors with unequal lengths")
+
+        elif is_timedelta64_dtype(other):
+            # let numpy handle it
+            return other / self._data
+
+        elif is_object_dtype(other):
+            # Note: unlike in __truediv__, we do not _need_ to do type#
+            #  inference on the result.  It does not raise, a numeric array
+            #  is returned.  GH#23829
+            result = [other[n] / self[n] for n in range(len(self))]
+            return np.array(result)
+
+        else:
+            raise TypeError("Cannot divide {dtype} data by {cls}"
+                            .format(dtype=other.dtype,
+                                    cls=type(self).__name__))
+
     if compat.PY2:
         __div__ = __truediv__
+        __rdiv__ = __rtruediv__
 
     # Note: TimedeltaIndex overrides this in call to cls._add_numeric_methods
     def __neg__(self):

pandas/core/indexes/base.py

@@ -5021,11 +5021,14 @@ def _add_numeric_methods_binary(cls):
         cls.__mod__ = _make_arithmetic_op(operator.mod, cls)
         cls.__floordiv__ = _make_arithmetic_op(operator.floordiv, cls)
         cls.__rfloordiv__ = _make_arithmetic_op(ops.rfloordiv, cls)
-        cls.__truediv__ = _make_arithmetic_op(operator.truediv, cls)
-        cls.__rtruediv__ = _make_arithmetic_op(ops.rtruediv, cls)
-        if not compat.PY3:
-            cls.__div__ = _make_arithmetic_op(operator.div, cls)
-            cls.__rdiv__ = _make_arithmetic_op(ops.rdiv, cls)
+
+        if not issubclass(cls, ABCTimedeltaIndex):
+            # GH#23829 TimedeltaIndex defines these directly
+            cls.__truediv__ = _make_arithmetic_op(operator.truediv, cls)
+            cls.__rtruediv__ = _make_arithmetic_op(ops.rtruediv, cls)
+            if not compat.PY3:
+                cls.__div__ = _make_arithmetic_op(operator.div, cls)
+                cls.__rdiv__ = _make_arithmetic_op(ops.rdiv, cls)
 
         cls.__divmod__ = _make_arithmetic_op(divmod, cls)
 

pandas/core/indexes/timedeltas.py

@@ -248,11 +248,8 @@ def _format_native_types(self, na_rep=u'NaT', date_format=None, **kwargs):
 
     __mul__ = Index.__mul__
     __rmul__ = Index.__rmul__
-    __truediv__ = Index.__truediv__
     __floordiv__ = Index.__floordiv__
     __rfloordiv__ = Index.__rfloordiv__
-    if compat.PY2:
-        __div__ = Index.__div__
 
     days = wrap_field_accessor(TimedeltaArray.days)
     seconds = wrap_field_accessor(TimedeltaArray.seconds)
@@ -261,6 +258,26 @@ def _format_native_types(self, na_rep=u'NaT', date_format=None, **kwargs):
 
     total_seconds = wrap_array_method(TimedeltaArray.total_seconds, True)
 
+    def __truediv__(self, other):
+        oth = other
+        if isinstance(other, Index):
+            # TimedeltaArray defers, so we need to unwrap
+            oth = other._values
+        result = TimedeltaArray.__truediv__(self, oth)
+        return wrap_arithmetic_op(self, other, result)
+
+    def __rtruediv__(self, other):
+        oth = other
+        if isinstance(other, Index):
+            # TimedeltaArray defers, so we need to unwrap
+            oth = other._values
+        result = TimedeltaArray.__rtruediv__(self, oth)
+        return wrap_arithmetic_op(self, other, result)
+
+    if compat.PY2:
+        __div__ = __truediv__
+        __rdiv__ = __rtruediv__
+
     # Compat for frequency inference, see GH#23789
     _is_monotonic_increasing = Index.is_monotonic_increasing
     _is_monotonic_decreasing = Index.is_monotonic_decreasing