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BUG: Series.argsort failing on datetime64[ns] when NaT present, GH #2967 #2977

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merged 1 commit into from
Mar 6, 2013
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BUG: Series.argsort failing on datetime64[ns] when NaT present, GH #2967 #2977

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2 changes: 2 additions & 0 deletions RELEASE.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -125,6 +125,7 @@ pandas 0.11.0
- Support idxmin/idxmax in a Series (but with no NaT)

- Bug on in-place putmasking on an ``integer`` series that needs to be converted to ``float`` (GH2746_)
- Bug in argsort of ``datetime64[ns]`` Series with ``NaT`` (GH2967_)

.. _GH622: https://github.com/pydata/pandas/issues/622
.. _GH797: https://github.com/pydata/pandas/issues/797
Expand All @@ -145,6 +146,7 @@ pandas 0.11.0
.. _GH2909: https://github.com/pydata/pandas/issues/2909
.. _GH2931: https://github.com/pydata/pandas/issues/2931
.. _GH2973: https://github.com/pydata/pandas/issues/2973
.. _GH2967: https://github.com/pydata/pandas/issues/2967


pandas 0.10.1
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9 changes: 5 additions & 4 deletions pandas/core/series.py
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Expand Up @@ -2092,16 +2092,17 @@ def argsort(self, axis=0, kind='quicksort', order=None):

Returns
-------
argsorted : Series
argsorted : Series, with -1 indicated where nan values are present

"""
values = self.values
mask = isnull(values)

if mask.any():
result = values.copy()
result = Series(-1,index=self.index,name=self.name)
notmask = -mask
result[notmask] = np.argsort(values[notmask], kind=kind)
return Series(result, index=self.index, name=self.name)
result.values[notmask] = np.argsort(self.values[notmask], kind=kind)
return result
else:
return Series(np.argsort(values, kind=kind), index=self.index,
name=self.name)
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15 changes: 15 additions & 0 deletions pandas/tests/test_series.py
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Expand Up @@ -1404,6 +1404,21 @@ def test_argsort(self):
argsorted = self.ts.argsort()
self.assert_(issubclass(argsorted.dtype.type, np.integer))

# GH 2967 (introduced bug in 0.11-dev I think)
s = Series([Timestamp('201301%02d'% (i+1)) for i in range(5)])
self.assert_(s.dtype == 'datetime64[ns]')
shifted = s.shift(-1)
self.assert_(shifted.dtype == 'datetime64[ns]')
self.assert_(isnull(shifted[4]) == True)

result = s.argsort()
expected = Series(range(5),dtype='int64')
assert_series_equal(result,expected)

result = shifted.argsort()
expected = Series(range(4) + [-1],dtype='int64')
assert_series_equal(result,expected)

def test_argsort_stable(self):
s = Series(np.random.randint(0, 100, size=10000))
mindexer = s.argsort(kind='mergesort')
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