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API: DataFrame.take always returns a copy #30784

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Merged
merged 12 commits into from
Jan 27, 2020
Merged

API: DataFrame.take always returns a copy #30784

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e532bc0
API: DataFrame.take always returns a copy
jorisvandenbossche Jan 7, 2020
2c9af9e
Merge remote-tracking branch 'upstream/master' into take-no_copy
jorisvandenbossche Jan 23, 2020
8c17091
add private _take_with_is_copy to use in indexing code
jorisvandenbossche Jan 23, 2020
d9e75f8
also deprecate it for Series
jorisvandenbossche Jan 23, 2020
e8e5cbb
update whatsnew message
jorisvandenbossche Jan 23, 2020
6c023d2
fixup whatsnew
jorisvandenbossche Jan 23, 2020
d15639d
fix typo
jorisvandenbossche Jan 23, 2020
11e597d
Merge remote-tracking branch 'upstream/master' into take-no_copy
jorisvandenbossche Jan 24, 2020
e519485
add tests for sample and asof
jorisvandenbossche Jan 24, 2020
b2afdf2
Merge remote-tracking branch 'upstream/master' into take-no_copy
jorisvandenbossche Jan 26, 2020
f10bd49
update docstring
jorisvandenbossche Jan 26, 2020
d3684f7
restore comment
jorisvandenbossche Jan 26, 2020
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16 changes: 3 additions & 13 deletions pandas/core/generic.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3356,12 +3356,10 @@ class max_speed
if is_copy is not None:
warnings.warn(
"is_copy is deprecated and will be removed in a future version. "
"take will always return a copy in the future.",
"take always returns a copy, so there is no need to specify this.",
FutureWarning,
stacklevel=2,
)
else:
is_copy = True

nv.validate_take(tuple(), kwargs)

Expand All @@ -3370,14 +3368,7 @@ class max_speed
new_data = self._data.take(
indices, axis=self._get_block_manager_axis(axis), verify=True
)
result = self._constructor(new_data).__finalize__(self)

# Maybe set copy if we didn't actually change the index.
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not sure if its relevant, but DTI.take sometimes returns a view

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In the case the indices can represent a slice, right?
Personally I don't think we should make that optimization, as IMO it is much clearer for take to always be a copy, but I suppose for Index which is supposed to be immutable it might matter less.

if is_copy:
if not result._get_axis(axis).equals(self._get_axis(axis)):
result._set_is_copy(self)

return result
return self._constructor(new_data).__finalize__(self)

def xs(self, key, axis=0, level=None, drop_level: bool_t = True):
"""
Expand Down Expand Up @@ -7022,8 +7013,7 @@ def asof(self, where, subset=None):

# mask the missing
missing = locs == -1
d = self.take(locs)
data = d.copy()
data = self.take(locs)
data.index = where
data.loc[missing] = np.nan
return data if is_list else data.iloc[-1]
Expand Down