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PERF: Avoid copy in DataFrame._reduce corner cases #42232

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Merged
merged 1 commit into from
Jun 25, 2021
Merged

PERF: Avoid copy in DataFrame._reduce corner cases #42232

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8 changes: 6 additions & 2 deletions pandas/core/frame.py
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Original file line number Diff line number Diff line change
Expand Up @@ -9810,8 +9810,12 @@ def _reduce(
FutureWarning,
stacklevel=5,
)
cols = self.columns[~dtype_is_dt]
self = self[cols]
# Non-copy equivalent to
# cols = self.columns[~dtype_is_dt]
# self = self[cols]
predicate = lambda x: not is_datetime64_any_dtype(x.dtype)
mgr = self._mgr._get_data_subset(predicate)
self = type(self)(mgr)

# TODO: Make other agg func handle axis=None properly GH#21597
axis = self._get_axis_number(axis)
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4 changes: 4 additions & 0 deletions pandas/core/internals/managers.py
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Expand Up @@ -479,6 +479,10 @@ def is_view(self) -> bool:

return False

def _get_data_subset(self: T, predicate: Callable) -> T:
blocks = [blk for blk in self.blocks if predicate(blk.values)]
return self._combine(blocks, copy=False)

def get_bool_data(self: T, copy: bool = False) -> T:
"""
Select blocks that are bool-dtype and columns from object-dtype blocks
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