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fix Timedelta.__mul__(NaT) #19819

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Merged
merged 2 commits into from
Feb 22, 2018
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fix Timedelta.__mul__(NaT) #19819

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423ce70
fix Timedelta.__mul__(NaT)
jbrockmendel Feb 21, 2018
7d0d558
update GH reference
jbrockmendel Feb 21, 2018
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1 change: 1 addition & 0 deletions doc/source/whatsnew/v0.23.0.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -735,6 +735,7 @@ Datetimelike
Timedelta
^^^^^^^^^

- Bug in :func:`Timedelta.__mul__` where multiplying by ``NaT`` returned ``NaT`` instead of raising a ``TypeError`` (:issue:`19819`)
- Bug in :class:`Series` with ``dtype='timedelta64[ns]`` where addition or subtraction of ``TimedeltaIndex`` had results cast to ``dtype='int64'`` (:issue:`17250`)
- Bug in :class:`Series` with ``dtype='timedelta64[ns]`` where addition or subtraction of ``TimedeltaIndex`` could return a ``Series`` with an incorrect name (:issue:`19043`)
- Bug in :func:`Timedelta.__floordiv__` and :func:`Timedelta.__rfloordiv__` dividing by many incompatible numpy objects was incorrectly allowed (:issue:`18846`)
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2 changes: 1 addition & 1 deletion pandas/_libs/tslibs/timedeltas.pyx
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Expand Up @@ -1057,7 +1057,7 @@ class Timedelta(_Timedelta):
return other * self.to_timedelta64()

elif other is NaT:
return NaT
raise TypeError('Cannot multiply Timedelta with NaT')

elif not (is_integer_object(other) or is_float_object(other)):
# only integers and floats allowed
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10 changes: 10 additions & 0 deletions pandas/tests/scalar/timedelta/test_arithmetic.py
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Expand Up @@ -216,6 +216,16 @@ class TestTimedeltaMultiplicationDivision(object):
# ---------------------------------------------------------------
# Timedelta.__mul__, __rmul__

@pytest.mark.parametrize('td_nat', [pd.NaT,
np.timedelta64('NaT', 'ns'),
np.timedelta64('NaT')])
@pytest.mark.parametrize('op', [operator.mul, ops.rmul])
def test_td_mul_nat(self, op, td_nat):
# GH#19819
td = Timedelta(10, unit='d')
with pytest.raises(TypeError):
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why do we raise on this again? what is the behavior on divide?

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For the same reason we raise on Timedelta * timedelta (or Timedelta * datetime depending on what hat pd.NaT is wearing).

For division Timedelta / pd.NaT returns np.nan, which is already correct.

op(td, td_nat)

@pytest.mark.parametrize('op', [operator.mul, ops.rmul])
def test_td_mul_scalar(self, op):
# GH#19738
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5 changes: 0 additions & 5 deletions pandas/tests/scalar/timedelta/test_timedelta.py
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Expand Up @@ -62,11 +62,6 @@ def test_unary_ops(self):
assert abs(-td) == td
assert abs(-td) == Timedelta('10d')

def test_binary_ops_nat(self):
td = Timedelta(10, unit='d')
# FIXME: The next test is wrong: td * NaT should raise
assert (td * pd.NaT) is pd.NaT


class TestTimedeltaComparison(object):
def test_comparison_object_array(self):
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