Improved the type stubs in the _libs directory to help with type checking

pandas/_libs/interval.pyi

@@ -0,0 +1,46 @@
+from typing import FrozenSet, Tuple
+
+import numpy as np
+
+class IntervalMixin:
+    @property
+    def _left(self) -> object: ...
+    @property
+    def _right(self) -> object: ...
+    @property
+    def closed_left(self) -> bool: ...
+    @property
+    def closed_right(self) -> bool: ...
+    @property
+    def open_left(self) -> bool: ...
+    @property
+    def open_right(self) -> bool: ...
+    @property
+    def mid(self) -> float: ...
+    @property
+    def length(self) -> float: ...
+    @property
+    def is_empty(self) -> bool: ...
+    def _check_closed_matches(self, other: IntervalMixin, name: str = ...) -> None: ...
+
+class Interval(IntervalMixin):
+    def __init__(self, left: object, right: object, closed: str = ...) -> None: ...
+    @property
+    def closed(self) -> str: ...
+    @property
+    def left(self) -> object: ...
+    @property
+    def right(self) -> object: ...
+    def __str__(self) -> str: ...
+    def __add__(self, y: Interval) -> Interval: ...
+    def __sub__(self, y: Interval) -> Interval: ...
+    def __mul__(self, y: Interval) -> Interval: ...
+    def __trudeiv__(self, y: Interval) -> Interval: ...
+    def __floordiv__(self, y: Interval) -> Interval: ...
+    def __overlaps__(self, other: Interval) -> bool: ...
+
+VALID_CLOSED: FrozenSet[str]
+
+def intervals_to_interval_bounds(
+    intervals: np.ndarray, valdiate_closed: bool = ...
+) -> Tuple[object, object, str]: ...

pandas/_libs/missing.pyi

@@ -0,0 +1,8 @@
+class C_NAType: ...
+class NAType(C_NAType): ...
+
+NA: NAType
+
+def is_matching_na(
+    left: object, right: object, nan_matches_none: bool = ...
+) -> bool: ...

pandas/_libs/properties.pyi

@@ -0,0 +1 @@
+cache_readonly = property

pandas/_libs/tslibs/ccalendar.pyi

@@ -8,5 +8,7 @@ def get_firstbday(year: int, month: int) -> int: ...
 def get_lastbday(year: int, month: int) -> int: ...
 def get_day_of_year(year: int, month: int, day: int) -> int: ...
 def get_iso_calendar(year: int, month: int, day: int) -> tuple[int, int, int]: ...
+def is_leapyear(year: int) -> bool: ...
 def get_week_of_year(year: int, month: int, day: int) -> int: ...
 def get_days_in_month(year: int, month: int) -> int: ...
+def dayofweek(y: int, m: int, d: int) -> int: ...

pandas/_libs/tslibs/dtypes.pyi

@@ -16,33 +16,33 @@ class PeriodDtypeBase:
     def from_date_offset(cls, offset: BaseOffset) -> PeriodDtypeBase: ...
 
 class FreqGroup(Enum):
-    FR_ANN: int = ...
-    FR_QTR: int = ...
-    FR_MTH: int = ...
-    FR_WK: int = ...
-    FR_BUS: int = ...
-    FR_DAY: int = ...
-    FR_HR: int = ...
-    FR_MIN: int = ...
-    FR_SEC: int = ...
-    FR_MS: int = ...
-    FR_US: int = ...
-    FR_NS: int = ...
-    FR_UND: int = ...
+    FR_ANN: int
+    FR_QTR: int
+    FR_MTH: int
+    FR_WK: int
+    FR_BUS: int
+    FR_DAY: int
+    FR_HR: int
+    FR_MIN: int
+    FR_SEC: int
+    FR_MS: int
+    FR_US: int
+    FR_NS: int
+    FR_UND: int
     @staticmethod
     def get_freq_group(code: int) -> FreqGroup: ...
 
 class Resolution(Enum):
-    RESO_NS: int = ...
-    RESO_US: int = ...
-    RESO_MS: int = ...
-    RESO_SEC: int = ...
-    RESO_MIN: int = ...
-    RESO_HR: int = ...
-    RESO_DAY: int = ...
-    RESO_MTH: int = ...
-    RESO_QTR: int = ...
-    RESO_YR: int = ...
+    RESO_NS: int
+    RESO_US: int
+    RESO_MS: int
+    RESO_SEC: int
+    RESO_MIN: int
+    RESO_HR: int
+    RESO_DAY: int
+    RESO_MTH: int
+    RESO_QTR: int
+    RESO_YR: int
     def __lt__(self, other: Resolution) -> bool: ...
     def __ge__(self, other: Resolution) -> bool: ...
     @property

pandas/_libs/tslibs/nattype.pyi

@@ -13,6 +13,7 @@ iNaT: int
 nat_strings: set[str]
 
 def is_null_datetimelike(val: object, inat_is_null: bool = ...) -> bool: ...
+def checknull_with_nat(val: object) -> bool: ...
 
 class NaTType(datetime):
     value: np.int64

pandas/_libs/tslibs/np_datetime.pyi

@@ -0,0 +1 @@
+class OutOfBoundsDatetime(ValueError): ...

pandas/_libs/tslibs/offsets.pyi

@@ -0,0 +1,106 @@
+from __future__ import annotations
+from datetime import datetime
+from typing import Any, Tuple, Union
+from datetime import timedelta
+
+class BaseOffset:
+    def __init__(self, n: int = ..., normalize: bool = ...) -> None: ...
+    def __eq__(self, other) -> bool: ...
+    def __ne__(self, other) -> bool: ...
+    def __hash__(self) -> int: ...
+    @property
+    def kwds(self) -> dict: ...
+    @property
+    def base(self) -> BaseOffset: ...
+    def __add__(self, other) -> BaseOffset: ...
+    def __sub__(self, other) -> BaseOffset: ...
+    def __call__(self, other): ...
+    def __mul__(self, other): ...
+    def __neg__(self) -> BaseOffset: ...
+    def copy(self) -> BaseOffset: ...
+    def __repr__(self) -> str: ...
+    @property
+    def name(self) -> str: ...
+    @property
+    def rule_code(self) -> str: ...
+    def freqstr(self) -> str: ...
+    # Next one is problematic due to circular imports
+    # def apply_index(self, dtindex: DatetimeIndex) -> DatetimeIndex: ...
+    def apply_index(self, dtindex): ...
+    def _apply_array(self, dtarr) -> None: ...
+    def rollback(self, dt: datetime) -> datetime: ...
+    def rollforward(self, dt: datetime) -> datetime: ...
+    def is_on_offset(self, dt: datetime) -> bool: ...
+    def __setstate__(self, state) -> None: ...
+    def __getstate__(self): ...
+    @property
+    def nanos(self) -> int: ...
+    def onOffset(self, dt: datetime) -> bool: ...
+    def isAnchored(self) -> bool: ...
+    def is_anchored(self) -> bool: ...
+
+class SingleConstructorOffset(BaseOffset):
+    @classmethod
+    def _from_name(cls, suffix=None): ...
+    def __reduce__(self): ...
+
+def to_offset(
+    freq: Union[str, Tuple, timedelta, BaseOffset, None]
+) -> Union[BaseOffset, None]: ...
+
+class Tick(SingleConstructorOffset):
+    def __init__(self, n: int = ..., normalize: bool = ...) -> None: ...
+
+class Day(Tick): ...
+class Hour(Tick): ...
+class Minute(Tick): ...
+class Second(Tick): ...
+class Milli(Tick): ...
+class Micro(Tick): ...
+class Nano(Tick): ...
+
+class RelativeDeltaOffset(BaseOffset):
+    def __init__(self, n: int = ..., normalize: bool = ..., **kwds: Any) -> None: ...
+
+class BusinessMixin(SingleConstructorOffset): ...
+class BusinessDay(BusinessMixin): ...
+class BusinessHour(BusinessMixin): ...
+class WeekOfMonthMixin(SingleConstructorOffset): ...
+class YearOffset(SingleConstructorOffset): ...
+class BYearEnd(YearOffset): ...
+class BYearBegin(YearOffset): ...
+class YearEnd(YearOffset): ...
+class YearBegin(YearOffset): ...
+class QuarterOffset(SingleConstructorOffset): ...
+class BQuarterEnd(QuarterOffset): ...
+class BQuarterBegin(QuarterOffset): ...
+class QuarterEnd(QuarterOffset): ...
+class QuarterBegin(QuarterOffset): ...
+class MonthOffset(SingleConstructorOffset): ...
+class MonthEnd(MonthOffset): ...
+class MonthBegin(MonthOffset): ...
+class BusinessMonthEnd(MonthOffset): ...
+class BusinessMonthBegin(MonthOffset): ...
+class SemiMonthOffset(SingleConstructorOffset): ...
+class SemiMonthEnd(SemiMonthOffset): ...
+class SemiMonthBegin(SemiMonthOffset): ...
+class Week(SingleConstructorOffset): ...
+class WeekOfMonth(WeekOfMonthMixin): ...
+class LastWeekOfMonth(WeekOfMonthMixin): ...
+class FY5253Mixin(SingleConstructorOffset): ...
+class FY5253(FY5253Mixin): ...
+class FY5253Quarter(FY5253Mixin): ...
+class Easter(SingleConstructorOffset): ...
+class _CustomBusinessMonth(BusinessMixin): ...
+class CustomBusinessDay(BusinessDay): ...
+class CustomBusinessHour(BusinessHour): ...
+class CustomBusinessMonthEnd(_CustomBusinessMonth): ...
+class CustomBusinessMonthBegin(_CustomBusinessMonth): ...
+class DateOffset(RelativeDeltaOffset): ...
+
+BDay = BusinessDay
+BMonthEnd = BusinessMonthEnd
+BMonthBegin = BusinessMonthBegin
+CBMonthEnd = CustomBusinessMonthEnd
+CBMonthBegin = CustomBusinessMonthBegin
+CDay = CustomBusinessDay

pandas/_libs/tslibs/period.pyi

@@ -1,3 +1,4 @@
+from datetime import datetime
 from typing import Literal
 
 import numpy as np
@@ -14,6 +15,9 @@ from pandas._typing import (
 INVALID_FREQ_ERR_MSG: str
 DIFFERENT_FREQ: str
 
+def is_period_object(obj: object) -> bool: ...
+def get_period_ordinal(dts: datetime, freq: int) -> int: ...
+
 class IncompatibleFrequency(ValueError): ...
 
 def periodarr_to_dt64arr(

pandas/_libs/tslibs/timestamps.pyi

@@ -18,7 +18,6 @@ import numpy as np
 
 from pandas._libs.tslibs import (
     BaseOffset,
-    NaT,
     NaTType,
     Period,
     Timedelta,