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allow callable in .loc #509

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Merged
merged 2 commits into from
Jan 13, 2023
Merged

allow callable in .loc #509

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905ec28
allow callable in .loc
Dr-Irv Jan 12, 2023
fdf4e03
merge in current main
Dr-Irv Jan 13, 2023
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13 changes: 11 additions & 2 deletions pandas-stubs/core/frame.pyi
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Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,7 @@ class _LocIndexerFrame(_LocIndexer):
self,
idx: IndexType
| MaskType
| Callable[[DataFrame], IndexType | MaskType | list[HashableT]]
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Does pandas support callables for both index and columns? Might need to also add it to the tuple format.

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Does pandas support callables for both index and columns? Might need to also add it to the tuple format.

Yes. Question is whether I try to get this right now (and create some tests), or wait for a bug report. If you think I should add it now, let me know and I'll give it a shot.

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I'm fine adding annotations as needed :) Only popped out because in one place a plain Callable is used and in the other place the argument/return type is specified.

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Happy to merge after the conflict with main is resolved

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should be done in fdf4e03

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I'm fine adding annotations as needed :) Only popped out because in one place a plain Callable is used and in the other place the argument/return type is specified.

Yes, I saw that and decided not to try to fix it. The other issue is that we match on a Hashable and any Callable works there too.

| list[HashableT]
| tuple[
IndexType | MaskType | list[HashableT] | Hashable,
Expand All @@ -167,14 +168,22 @@ class _LocIndexerFrame(_LocIndexer):
def __getitem__(
self,
idx: tuple[
int | StrLike | tuple[Scalar, ...], int | StrLike | tuple[Scalar, ...]
int | StrLike | tuple[Scalar, ...] | Callable[[DataFrame], ScalarT],
int | StrLike | tuple[Scalar, ...],
],
) -> Scalar: ...
@overload
def __getitem__(
self,
idx: ScalarT
| tuple[IndexType | MaskType | _IndexSliceTuple, ScalarT | None]
| Callable[[DataFrame], ScalarT]
| tuple[
IndexType
| MaskType
| _IndexSliceTuple
| Callable[[DataFrame], ScalarT | list[HashableT] | IndexType | MaskType],
ScalarT | None,
]
| None,
) -> Series: ...
@overload
Expand Down
22 changes: 22 additions & 0 deletions tests/test_frame.py
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Expand Up @@ -22,6 +22,7 @@
TypedDict,
TypeVar,
Union,
cast,
)

import numpy as np
Expand Down Expand Up @@ -2366,6 +2367,27 @@ def test_frame_dropna_subset() -> None:
)


def test_loc_callable() -> None:
# GH 256
df = pd.DataFrame({"x": [1, 2, 3], "y": [4, 5, 6]})

def select1(df: pd.DataFrame) -> pd.Series:
return df["x"] > 2.0

check(assert_type(df.loc[select1], pd.DataFrame), pd.DataFrame)
check(assert_type(df.loc[select1, :], pd.DataFrame), pd.DataFrame)

def select2(df: pd.DataFrame) -> list[Hashable]:
return [i for i in df.index if cast(int, i) % 2 == 1]

check(assert_type(df.loc[select2, "x"], pd.Series), pd.Series)

def select3(df: pd.DataFrame) -> int:
return 1

check(assert_type(df.loc[select3, "x"], Scalar), np.integer)


def test_npint_loc_indexer() -> None:
# GH 508

Expand Down