Y026: explicitly declare type aliases as TypeAlias

.pre-commit-config.yaml

@@ -30,7 +30,7 @@ repos:
         - flake8-pyi==22.8.2
         types: [pyi]
         args: [
-          --ignore=E301 E302 E305 E402 E501 E701 E704 F401 F811 W503 Y019 Y026 Y027 Y034 Y037 Y041,
+          --ignore=E301 E302 E305 E402 E501 E701 E704 F401 F811 W503 Y019 Y027 Y034 Y037 Y041 Y042,
           # TypeVars in private files are already private
           --per-file-ignores=_*.pyi:Y001
         ]

pandas-stubs/_libs/tslibs/nattype.pyi

@@ -6,14 +6,17 @@ from datetime import (
 from typing import Union
 
 import numpy as np
+from typing_extensions import TypeAlias
 
 from pandas._libs.tslibs.period import Period
 
 NaT: NaTType
 iNaT: int
 nat_strings: set[str]
 
-_NaTComparisonTypes = Union[datetime, timedelta, Period, np.datetime64, np.timedelta64]
+_NaTComparisonTypes: TypeAlias = Union[
+    datetime, timedelta, Period, np.datetime64, np.timedelta64
+]
 
 class _NatComparison:
     def __call__(self, other: _NaTComparisonTypes) -> bool: ...

pandas-stubs/_libs/tslibs/timedeltas.pyi

@@ -7,6 +7,7 @@ from typing import (
 )
 
 import numpy as np
+from typing_extensions import TypeAlias
 
 from pandas._libs.tslibs import (
     NaTType,
@@ -16,7 +17,7 @@ from pandas._typing import npt
 
 # This should be kept consistent with the keys in the dict timedelta_abbrevs
 # in pandas/_libs/tslibs/timedeltas.pyx
-UnitChoices = Literal[
+UnitChoices: TypeAlias = Literal[
     "Y",
     "y",
     "M",

pandas-stubs/_typing.pyi

@@ -1,17 +1,8 @@
 from builtins import type as type_t
 import datetime
-from io import (
-    BufferedIOBase,
-    RawIOBase,
-    TextIOBase,
-    TextIOWrapper,
-)
-from mmap import mmap
 from os import PathLike
 from typing import (
-    IO,
     Any,
-    AnyStr,
     Callable,
     Hashable,
     Iterator,
@@ -32,6 +23,7 @@ from pandas.core.generic import NDFrame
 from pandas.core.groupby.grouper import Grouper
 from pandas.core.indexes.base import Index
 from pandas.core.series import Series
+from typing_extensions import TypeAlias
 
 from pandas._libs.tslibs import (
     Period,
@@ -43,22 +35,28 @@ from pandas.core.dtypes.dtypes import ExtensionDtype
 
 from pandas.io.formats.format import EngFormatter
 
-ArrayLike = Union[ExtensionArray, np.ndarray]
-AnyArrayLike = Union[Index, Series, np.ndarray]
-PythonScalar = Union[str, bool, complex]
+ArrayLike: TypeAlias = Union[ExtensionArray, np.ndarray]
+AnyArrayLike: TypeAlias = Union[Index, Series, np.ndarray]
+PythonScalar: TypeAlias = Union[str, bool, complex]
 DatetimeLikeScalar = TypeVar("DatetimeLikeScalar", Period, Timestamp, Timedelta)
-PandasScalar = Union[bytes, datetime.date, datetime.datetime, datetime.timedelta]
-# Scalar = Union[PythonScalar, PandasScalar]
+PandasScalar: TypeAlias = Union[
+    bytes, datetime.date, datetime.datetime, datetime.timedelta
+]
+# Scalar: TypeAlias = Union[PythonScalar, PandasScalar]
 
-DatetimeLike = Union[datetime.date, datetime.datetime, np.datetime64, Timestamp]
+DatetimeLike: TypeAlias = Union[
+    datetime.date, datetime.datetime, np.datetime64, Timestamp
+]
 
 # dtypes
-NpDtype = Union[str, np.dtype[np.generic], type[Union[str, complex, bool, object]]]
-Dtype = Union[ExtensionDtype, NpDtype]
-AstypeArg = Union[ExtensionDtype, npt.DTypeLike]
+NpDtype: TypeAlias = Union[
+    str, np.dtype[np.generic], type[Union[str, complex, bool, object]]
+]
+Dtype: TypeAlias = Union[ExtensionDtype, NpDtype]
+AstypeArg: TypeAlias = Union[ExtensionDtype, npt.DTypeLike]
 # DtypeArg specifies all allowable dtypes in a functions its dtype argument
-DtypeArg = Union[Dtype, dict[Any, Dtype]]
-DtypeObj = Union[np.dtype[np.generic], ExtensionDtype]
+DtypeArg: TypeAlias = Union[Dtype, dict[Any, Dtype]]
+DtypeObj: TypeAlias = Union[np.dtype[np.generic], ExtensionDtype]
 
 # filenames and file-like-objects
 AnyStr_cov = TypeVar("AnyStr_cov", str, bytes, covariant=True)
@@ -91,47 +89,48 @@ class ReadCsvBuffer(ReadBuffer[AnyStr_cov], Protocol[AnyStr_cov]):
 class WriteExcelBuffer(WriteBuffer[bytes], Protocol):
     def truncate(self, size: int | None = ...) -> int: ...
 
-FilePath = Union[str, PathLike[str]]
-FilePathOrBuffer = Union[
-    FilePath, IO[AnyStr], RawIOBase, BufferedIOBase, TextIOBase, TextIOWrapper, mmap
-]
-
-Axis = Union[str, int]
-IndexLabel = Union[Hashable, Sequence[Hashable]]
-Label = Optional[Hashable]
-Level = Union[Hashable, int]
-Suffixes = tuple[Optional[str], Optional[str]]
-Ordered = Optional[bool]
-JSONSerializable = Union[PythonScalar, list, dict]
-Axes = Union[AnyArrayLike, list, dict, range]
-Renamer = Union[Mapping[Any, Label], Callable[[Any], Label]]
+FilePath: TypeAlias = Union[str, PathLike[str]]
+
+Axis: TypeAlias = Union[str, int]
+IndexLabel: TypeAlias = Union[Hashable, Sequence[Hashable]]
+Label: TypeAlias = Optional[Hashable]
+Level: TypeAlias = Union[Hashable, int]
+Suffixes: TypeAlias = tuple[Optional[str], Optional[str]]
+Ordered: TypeAlias = Optional[bool]
+JSONSerializable: TypeAlias = Union[PythonScalar, list, dict]
+Axes: TypeAlias = Union[AnyArrayLike, list, dict, range]
+Renamer: TypeAlias = Union[Mapping[Any, Label], Callable[[Any], Label]]
 T = TypeVar("T")
-FuncType = Callable[..., Any]
+FuncType: TypeAlias = Callable[..., Any]
 F = TypeVar("F", bound=FuncType)
 HashableT = TypeVar("HashableT", bound=Hashable)
 
-AggFuncTypeBase = Union[Callable, str, np.ufunc]
-AggFuncTypeDictSeries = dict[Hashable, AggFuncTypeBase]
-AggFuncTypeDictFrame = dict[Hashable, Union[AggFuncTypeBase, list[AggFuncTypeBase]]]
-AggFuncTypeSeriesToFrame = Union[
+AggFuncTypeBase: TypeAlias = Union[Callable, str, np.ufunc]
+AggFuncTypeDictSeries: TypeAlias = dict[Hashable, AggFuncTypeBase]
+AggFuncTypeDictFrame: TypeAlias = dict[
+    Hashable, Union[AggFuncTypeBase, list[AggFuncTypeBase]]
+]
+AggFuncTypeSeriesToFrame: TypeAlias = Union[
     list[AggFuncTypeBase],
     AggFuncTypeDictSeries,
 ]
-AggFuncTypeFrame = Union[
+AggFuncTypeFrame: TypeAlias = Union[
     AggFuncTypeBase,
     list[AggFuncTypeBase],
     AggFuncTypeDictFrame,
 ]
 
-num = complex
-SeriesAxisType = Literal["index", 0]  # Restricted subset of _AxisType for series
-AxisType = Literal["columns", "index", 0, 1]
+num: TypeAlias = complex
+SeriesAxisType: TypeAlias = Literal[
+    "index", 0
+]  # Restricted subset of _AxisType for series
+AxisType: TypeAlias = Literal["columns", "index", 0, 1]
 DtypeNp = TypeVar("DtypeNp", bound=np.dtype[np.generic])
-KeysArgType = Any
+KeysArgType: TypeAlias = Any
 ListLike = TypeVar("ListLike", Sequence, np.ndarray, "Series", "Index")
-ListLikeU = Union[Sequence, np.ndarray, Series, Index]
-StrLike = Union[str, np.str_]
-Scalar = Union[
+ListLikeU: TypeAlias = Union[Sequence, np.ndarray, Series, Index]
+StrLike: TypeAlias = Union[str, np.str_]
+Scalar: TypeAlias = Union[
     str,
     bytes,
     datetime.date,
@@ -146,14 +145,14 @@ Scalar = Union[
 ]
 ScalarT = TypeVar("ScalarT", bound=Scalar)
 # Refine the definitions below in 3.9 to use the specialized type.
-np_ndarray_int64 = npt.NDArray[np.int64]
-np_ndarray_int = npt.NDArray[np.signedinteger]
-np_ndarray_anyint = npt.NDArray[np.integer]
-np_ndarray_bool = npt.NDArray[np.bool_]
-np_ndarray_str = npt.NDArray[np.str_]
-
-IndexType = Union[slice, np_ndarray_int64, Index, list[int], Series[int]]
-MaskType = Union[Series[bool], np_ndarray_bool, list[bool]]
+np_ndarray_int64: TypeAlias = npt.NDArray[np.int64]
+np_ndarray_int: TypeAlias = npt.NDArray[np.signedinteger]
+np_ndarray_anyint: TypeAlias = npt.NDArray[np.integer]
+np_ndarray_bool: TypeAlias = npt.NDArray[np.bool_]
+np_ndarray_str: TypeAlias = npt.NDArray[np.str_]
+
+IndexType: TypeAlias = Union[slice, np_ndarray_int64, Index, list[int], Series[int]]
+MaskType: TypeAlias = Union[Series[bool], np_ndarray_bool, list[bool]]
 # Scratch types for generics
 S1 = TypeVar(
     "S1",
@@ -177,13 +176,13 @@ T1 = TypeVar(
 )
 T2 = TypeVar("T2", str, int)
 
-IndexingInt = Union[
+IndexingInt: TypeAlias = Union[
     int, np.int_, np.integer, np.unsignedinteger, np.signedinteger, np.int8
 ]
-TimestampConvertibleTypes = Union[
+TimestampConvertibleTypes: TypeAlias = Union[
     Timestamp, datetime.datetime, np.datetime64, np.int64, float, str
 ]
-TimedeltaConvertibleTypes = Union[
+TimedeltaConvertibleTypes: TypeAlias = Union[
     Timedelta, datetime.timedelta, np.timedelta64, np.int64, float, str
 ]
 # NDFrameT is stricter and ensures that the same subclass of NDFrame always is
@@ -196,39 +195,39 @@ IndexT = TypeVar("IndexT", bound=Index)
 
 # Interval closed type
 
-IntervalClosedType = Literal["left", "right", "both", "neither"]
+IntervalClosedType: TypeAlias = Literal["left", "right", "both", "neither"]
 
-DateTimeErrorChoices = Literal["ignore", "raise", "coerce"]
+DateTimeErrorChoices: TypeAlias = Literal["ignore", "raise", "coerce"]
 
 # Shared by functions such as drop and astype
-IgnoreRaise = Literal["ignore", "raise"]
+IgnoreRaise: TypeAlias = Literal["ignore", "raise"]
 
 # for arbitrary kwargs passed during reading/writing files
-StorageOptions = Optional[dict[str, Any]]
+StorageOptions: TypeAlias = Optional[dict[str, Any]]
 
 # compression keywords and compression
-CompressionDict = dict[str, Any]
-CompressionOptions = Optional[
+CompressionDict: TypeAlias = dict[str, Any]
+CompressionOptions: TypeAlias = Optional[
     Union[Literal["infer", "gzip", "bz2", "zip", "xz", "zstd"], CompressionDict]
 ]
-FormattersType = Union[
+FormattersType: TypeAlias = Union[
     list[Callable], tuple[Callable, ...], Mapping[Union[str, int], Callable]
 ]
-FloatFormatType = str | Callable | EngFormatter
+FloatFormatType: TypeAlias = str | Callable | EngFormatter
 # converters
-ConvertersArg = dict[Hashable, Callable[[Dtype], Dtype]]
+ConvertersArg: TypeAlias = dict[Hashable, Callable[[Dtype], Dtype]]
 
 # parse_dates
-ParseDatesArg = Union[
+ParseDatesArg: TypeAlias = Union[
     bool, list[Hashable], list[list[Hashable]], dict[Hashable, list[Hashable]]
 ]
 
 # read_xml parsers
-XMLParsers = Literal["lxml", "etree"]
+XMLParsers: TypeAlias = Literal["lxml", "etree"]
 
 # Any plain Python or numpy function
-Function = Union[np.ufunc, Callable[..., Any]]
-GroupByObjectNonScalar = Union[
+Function: TypeAlias = Union[np.ufunc, Callable[..., Any]]
+GroupByObjectNonScalar: TypeAlias = Union[
     tuple,
     list[HashableT],
     Function,
@@ -244,9 +243,9 @@ GroupByObjectNonScalar = Union[
     Grouper,
     list[Grouper],
 ]
-GroupByObject = Union[Scalar, GroupByObjectNonScalar]
+GroupByObject: TypeAlias = Union[Scalar, GroupByObjectNonScalar]
 
-StataDateFormat = Literal[
+StataDateFormat: TypeAlias = Literal[
     "tc",
     "%tc",
     "td",
@@ -263,37 +262,43 @@ StataDateFormat = Literal[
     "%ty",
 ]
 
-FillnaOptions = Literal["backfill", "bfill", "ffill", "pad"]
-ReplaceMethod = Literal["pad", "ffill", "bfill"]
-SortKind = Literal["quicksort", "mergesort", "heapsort", "stable"]
-NaPosition = Literal["first", "last"]
-MergeHow = Literal["left", "right", "outer", "inner"]
-JsonFrameOrient = Literal["split", "records", "index", "columns", "values", "table"]
-JsonSeriesOrient = Literal["split", "records", "index"]
+FillnaOptions: TypeAlias = Literal["backfill", "bfill", "ffill", "pad"]
+ReplaceMethod: TypeAlias = Literal["pad", "ffill", "bfill"]
+SortKind: TypeAlias = Literal["quicksort", "mergesort", "heapsort", "stable"]
+NaPosition: TypeAlias = Literal["first", "last"]
+MergeHow: TypeAlias = Literal["left", "right", "outer", "inner"]
+JsonFrameOrient: TypeAlias = Literal[
+    "split", "records", "index", "columns", "values", "table"
+]
+JsonSeriesOrient: TypeAlias = Literal["split", "records", "index"]
 
-TimestampConvention = Literal["start", "end", "s", "e"]
+TimestampConvention: TypeAlias = Literal["start", "end", "s", "e"]
 
-CSVEngine = Literal["c", "python", "pyarrow", "python-fwf"]
-CSVQuoting = Literal[0, 1, 2, 3]
+CSVEngine: TypeAlias = Literal["c", "python", "pyarrow", "python-fwf"]
+CSVQuoting: TypeAlias = Literal[0, 1, 2, 3]
 
-HDFCompLib = Literal["zlib", "lzo", "bzip2", "blosc"]
-ParquetEngine = Literal["auto", "pyarrow", "fastparquet"]
-FileWriteMode = Literal[
+HDFCompLib: TypeAlias = Literal["zlib", "lzo", "bzip2", "blosc"]
+ParquetEngine: TypeAlias = Literal["auto", "pyarrow", "fastparquet"]
+FileWriteMode: TypeAlias = Literal[
     "a", "w", "x", "at", "wt", "xt", "ab", "wb", "xb", "w+", "w+b", "a+", "a+b"
 ]
-ColspaceArgType = str | int | Sequence[int | str] | Mapping[Hashable, str | int]
+ColspaceArgType: TypeAlias = (
+    str | int | Sequence[int | str] | Mapping[Hashable, str | int]
+)
 
 # Windowing rank methods
-WindowingRankType = Literal["average", "min", "max"]
-WindowingEngine = Union[Literal["cython", "numba"], None]
+WindowingRankType: TypeAlias = Literal["average", "min", "max"]
+WindowingEngine: TypeAlias = Union[Literal["cython", "numba"], None]
 
 class _WindowingNumbaKwargs(TypedDict, total=False):
     nopython: bool
     nogil: bool
     parallel: bool
 
-WindowingEngineKwargs = Union[_WindowingNumbaKwargs, None]
-QuantileInterpolation = Literal["linear", "lower", "higher", "midpoint", "nearest"]
+WindowingEngineKwargs: TypeAlias = Union[_WindowingNumbaKwargs, None]
+QuantileInterpolation: TypeAlias = Literal[
+    "linear", "lower", "higher", "midpoint", "nearest"
+]
 
 class StyleExportDict(TypedDict, total=False):
     apply: Any
@@ -305,6 +310,6 @@ class StyleExportDict(TypedDict, total=False):
     hide_column_names: bool
     css: dict[str, str | int]
 
-CalculationMethod = Literal["single", "table"]
+CalculationMethod: TypeAlias = Literal["single", "table"]
 
 __all__ = ["npt", "type_t"]

pandas-stubs/_version.pyi

@@ -4,4 +4,4 @@ version_json: str = ...
 
 def get_versions(): ...
 
-_stub_version = Literal["1.5.0.220926"]
+_stub_version: Literal["1.5.0.220926"]

pandas-stubs/core/dtypes/common.pyi

@@ -2,6 +2,7 @@ from typing import Union
 
 import numpy as np
 import pandas as pd
+from typing_extensions import TypeAlias
 
 from pandas._typing import (
     ArrayLike,
@@ -28,7 +29,7 @@ from pandas.core.dtypes.inference import (
     is_scalar as is_scalar,
 )
 
-_ArrayOrDtype = Union[ArrayLike, npt.DTypeLike, pd.Series, pd.DataFrame]
+_ArrayOrDtype: TypeAlias = Union[ArrayLike, npt.DTypeLike, pd.Series, pd.DataFrame]
 
 def is_object_dtype(arr_or_dtype: _ArrayOrDtype) -> bool: ...
 def is_sparse(arr: ArrayLike | pd.Series | pd.DataFrame) -> bool: ...

pandas-stubs/core/dtypes/generic.pyi

@@ -1,5 +1,6 @@
 from pandas import Series
 from pandas.core.arrays import ExtensionArray
+from typing_extensions import TypeAlias
 
-ABCSeries = type[Series]
-ABCExtensionArray = type[ExtensionArray]
+ABCSeries: TypeAlias = type[Series]
+ABCExtensionArray: TypeAlias = type[ExtensionArray]