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Unary plus operator (Issue #16073) #16106

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7e71501
ENH: Unary plus operator, deals with issue #16073
wuisawesome Apr 24, 2017
af7512a
What's new
wuisawesome Apr 24, 2017
38d48c8
ENH: Unary plus operator, deals with issue #16073
wuisawesome Apr 24, 2017
2ec64d2
Merge branch 'unary_plus_operator' of github.com:wuisawesome/pandas i…
wuisawesome Apr 24, 2017
f10e3be
ENH: Unary plus operator, deals with issue #16073
wuisawesome Apr 24, 2017
2c09624
Operator edge cases, better tests
wuisawesome Apr 24, 2017
8f4d7ca
Merge remote-tracking branch 'pandas-dev/master' into unary_plus_oper…
wuisawesome Apr 24, 2017
c658f7f
Added double ticks to whats new
wuisawesome Apr 24, 2017
d932379
Merging
wuisawesome Apr 24, 2017
0ab9979
Merge remote-tracking branch 'pandas-dev/master' into unary_plus_oper…
wuisawesome Apr 24, 2017
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5 changes: 3 additions & 2 deletions doc/source/whatsnew/v0.20.0.txt
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Expand Up @@ -213,8 +213,7 @@ See :ref:`the docs here <io.pickle.compression>`

Using an explicit compression type

.. ipython:: python
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don't change other things in the file

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I'm not certain why this happened. The rest of the diff shows that the same identical line is added again, thus making no actual changes to the file


.. ipython:: python
df.to_pickle("data.pkl.compress", compression="gzip")
rt = pd.read_pickle("data.pkl.compress", compression="gzip")
rt
Expand Down Expand Up @@ -1196,6 +1195,8 @@ Other API Changes
- ``DataFrame`` and ``Panel`` constructors with invalid input will now raise ``ValueError`` rather than ``pandas.core.common.PandasError``, if called with scalar inputs and not axes; The exception ``PandasError`` is removed as well. (:issue:`15541`)
- The exception ``pandas.core.common.AmbiguousIndexError`` is removed as it is not referenced (:issue:`15541`)

- `Series` and `DataFrame` now have unary plus operators (:issue:`16073`). The plus operator behaves consistently with the unary minus operator.
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use double backticks here around Series, DataFrame. Put the issue reference at the end.



.. _whatsnew_0200.privacy:

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8 changes: 8 additions & 0 deletions pandas/core/generic.py
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Expand Up @@ -859,6 +859,14 @@ def _indexed_same(self, other):
return all([self._get_axis(a).equals(other._get_axis(a))
for a in self._AXIS_ORDERS])

def __pos__(self):
values = _values_from_object(self)
if values.dtype == np.bool_:
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something like:

if is_bool_dtype(values):
   ...
elif not (is_numeric_dtype(values) or is_timedelta64_dtype(values)):
   raise

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add the same logic to __neg__

arr = values #To remain consistent with __neg__
else:
arr = operator.pos(values)
return self.__array_wrap__(arr)

def __neg__(self):
values = _values_from_object(self)
if values.dtype == np.bool_:
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3 changes: 3 additions & 0 deletions pandas/tests/frame/test_operators.py
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Expand Up @@ -343,6 +343,9 @@ def test_logical_with_nas(self):
expected = Series([True, True])
assert_series_equal(result, expected)

def test_pos(self):
assert_frame_equal(+self.frame, 1 * self.frame)

def test_neg(self):
# what to do?
assert_frame_equal(-self.frame, -1 * self.frame)
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3 changes: 3 additions & 0 deletions pandas/tests/series/test_operators.py
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Expand Up @@ -91,6 +91,9 @@ def check(series, other, check_reverse=False):
check(self.ts, 5, check_reverse=True)
check(tm.makeFloatSeries(), tm.makeFloatSeries(), check_reverse=True)

def test_pos(self):
assert_series_equal(+self.series, 1 * self.series) #Ensures no rounding issues
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comment is not necessary


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add a couple of raise assertion on strings

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this would technically work on datetimes, but I think we should disallow this (pls add tests for __neg__ as well).

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e.g.

In [9]: -Series(list('abc'))
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-9-93660e79330e> in <module>()
----> 1 -Series(list('abc'))

/Users/jreback/pandas/pandas/core/generic.py in __neg__(self)
    865             arr = operator.inv(values)
    866         else:
--> 867             arr = operator.neg(values)
    868         return self.__array_wrap__(arr)
    869 

TypeError: bad operand type for unary -: 'str'

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In [10]: Series(pd.date_range('20130101', periods=3))
Out[10]: 
0   2013-01-01
1   2013-01-02
2   2013-01-03
dtype: datetime64[ns]

In [11]: -Series(pd.date_range('20130101', periods=3))
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-11-23bfb90f61eb> in <module>()
----> 1 -Series(pd.date_range('20130101', periods=3))

/Users/jreback/pandas/pandas/core/generic.py in __neg__(self)
    865             arr = operator.inv(values)
    866         else:
--> 867             arr = operator.neg(values)
    868         return self.__array_wrap__(arr)
    869 

TypeError: ufunc 'negative' did not contain a loop with signature matching types dtype('<M8[ns]') dtype('<M8[ns]')

In [12]: +Series(pd.date_range('20130101', periods=3))
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-12-b72a11ca274c> in <module>()
----> 1 +Series(pd.date_range('20130101', periods=3))

TypeError: bad operand type for unary +: 'Series'

I want [12] still to raise after this change.

def test_neg(self):
assert_series_equal(-self.series, -1 * self.series)

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