feat(arithmetic): ✖️ multiplication

pandas-stubs/core/arrays/datetimelike.pyi

@@ -60,7 +60,7 @@ class DatetimeLikeArrayMixin(ExtensionOpsMixin, ExtensionArray):
     @property
     def shape(self): ...
     def reshape(self, *args: Any, **kwargs: Any): ...
-    def ravel(self, *args: Any, **kwargs: Any): ...  # pyrefly: ignore
+    def ravel(self, *args: Any, **kwargs: Any): ...
     def __iter__(self): ...
     @property
     def asi8(self) -> np.ndarray: ...
@@ -85,7 +85,7 @@ class DatetimeLikeArrayMixin(ExtensionOpsMixin, ExtensionArray):
     def unique(self): ...
     def copy(self): ...
     def shift(self, periods: int = 1, fill_value=..., axis: int = ...): ...
-    def repeat(self, repeats, *args: Any, **kwargs: Any): ...  # pyrefly: ignore
+    def repeat(self, repeats, *args: Any, **kwargs: Any): ...
     def value_counts(self, dropna: bool = True): ...
     def map(self, mapper): ...
     def isna(self): ...

pandas-stubs/core/groupby/generic.pyi

@@ -57,7 +57,7 @@ class NamedAgg(NamedTuple):
 
 class SeriesGroupBy(GroupBy[Series[S2]], Generic[S2, ByT]):
     @overload
-    def aggregate(  # pyrefly: ignore
+    def aggregate(
         self,
         func: Callable[Concatenate[Series[S2], P], S3],
         /,

pandas-stubs/core/indexes/base.pyi

@@ -781,6 +781,16 @@ class Index(IndexOpsMixin[S1]):
         ),
     ) -> Index[Timedelta]: ...
     @overload
+    def __mul__(
+        self: Index[_str],
+        other: np_ndarray_float | np_ndarray_complex | np_ndarray_dt | np_ndarray_td,
+    ) -> Never: ...
+    @overload
+    def __mul__(
+        self: Index[_str],
+        other: int | Sequence[int] | np_ndarray_bool | np_ndarray_anyint | Index[T_INT],
+    ) -> Index[_str]: ...
+    @overload
     def __mul__(self: Index[T_INT], other: bool | Sequence[bool]) -> Index[T_INT]: ...
     @overload
     def __mul__(self: Index[float], other: int | Sequence[int]) -> Index[float]: ...
@@ -854,6 +864,16 @@ class Index(IndexOpsMixin[S1]):
         ),
     ) -> Index[Timedelta]: ...
     @overload
+    def __rmul__(
+        self: Index[_str],
+        other: np_ndarray_float | np_ndarray_complex | np_ndarray_dt | np_ndarray_td,
+    ) -> Never: ...
+    @overload
+    def __rmul__(
+        self: Index[_str],
+        other: int | Sequence[int] | np_ndarray_bool | np_ndarray_anyint | Index[T_INT],
+    ) -> Index[_str]: ...
+    @overload
     def __rmul__(self: Index[T_INT], other: bool | Sequence[bool]) -> Index[T_INT]: ...
     @overload
     def __rmul__(self: Index[float], other: int | Sequence[int]) -> Index[float]: ...
@@ -909,7 +929,7 @@ class Index(IndexOpsMixin[S1]):
 @type_check_only
 class _IndexSubclassBase(Index[S1], Generic[S1, GenericT_co]):
     @overload
-    def to_numpy(  # pyrefly: ignore
+    def to_numpy(
         self,
         dtype: None = None,
         copy: bool = False,

pandas-stubs/core/indexes/multi.pyi

@@ -109,7 +109,7 @@ class MultiIndex(Index):
     def dropna(self, how: AnyAll = "any") -> Self: ...
     def get_level_values(self, level: str | int) -> Index: ...
     def unique(self, level=...): ...
-    def to_frame(  # pyrefly: ignore
+    def to_frame(
         self,
         index: bool = True,
         name: list[HashableT] = ...,
@@ -131,7 +131,7 @@ class MultiIndex(Index):
     def __getitem__(  # pyright: ignore[reportIncompatibleMethodOverride]
         self, key: int
     ) -> tuple: ...
-    def append(self, other): ...  # pyrefly: ignore
+    def append(self, other): ...
     def repeat(self, repeats, axis=...): ...
     def drop(self, codes, level: Level | None = None, errors: str = "raise") -> Self: ...  # type: ignore[override] # pyright: ignore[reportIncompatibleMethodOverride]
     def swaplevel(self, i: int = -2, j: int = -1): ...

pandas-stubs/core/indexes/range.pyi

@@ -81,7 +81,7 @@ class RangeIndex(_IndexSubclassBase[int, np.int64]):
     def all(self, *args: Any, **kwargs: Any) -> bool: ...
     def any(self, *args: Any, **kwargs: Any) -> bool: ...
     @final
-    def union(  # pyrefly: ignore
+    def union(
         self, other: list[HashableT] | Index, sort: bool | None = None
     ) -> Index | Index[int] | RangeIndex: ...
     @overload  # type: ignore[override]

pandas-stubs/core/series.pyi

@@ -2583,6 +2583,23 @@ class Series(IndexOpsMixin[S1], NDFrame):
         ),
     ) -> Series[Timedelta]: ...
     @overload
+    def __mul__(
+        self: Series[_str],
+        other: np_ndarray_float | np_ndarray_complex | np_ndarray_dt | np_ndarray_td,
+    ) -> Never: ...
+    @overload
+    def __mul__(
+        self: Series[_str],
+        other: (
+            int
+            | Sequence[int]
+            | np_ndarray_bool
+            | np_ndarray_anyint
+            | Index[T_INT]
+            | Series[T_INT]
+        ),
+    ) -> Series[_str]: ...
+    @overload
     def __mul__(self: Series[T_INT], other: bool | Sequence[bool]) -> Series[T_INT]: ...
     @overload
     def __mul__(self: Series[float], other: int | Sequence[int]) -> Series[float]: ...
@@ -2675,6 +2692,21 @@ class Series(IndexOpsMixin[S1], NDFrame):
         axis: AxisIndex | None = 0,
     ) -> Series[Timedelta]: ...
     @overload
+    def mul(
+        self: Series[_str],
+        other: (
+            int
+            | Sequence[int]
+            | np_ndarray_bool
+            | np_ndarray_anyint
+            | Index[T_INT]
+            | Series[T_INT]
+        ),
+        level: Level | None = None,
+        fill_value: float | None = None,
+        axis: int = 0,
+    ) -> Series[_str]: ...
+    @overload
     def mul(
         self: Series[T_INT],
         other: bool | Sequence[bool],
@@ -2800,6 +2832,23 @@ class Series(IndexOpsMixin[S1], NDFrame):
         ),
     ) -> Series[Timedelta]: ...
     @overload
+    def __rmul__(
+        self: Series[_str],
+        other: np_ndarray_float | np_ndarray_complex | np_ndarray_dt | np_ndarray_td,
+    ) -> Never: ...
+    @overload
+    def __rmul__(
+        self: Series[_str],
+        other: (
+            int
+            | Sequence[int]
+            | np_ndarray_bool
+            | np_ndarray_anyint
+            | Index[T_INT]
+            | Series[T_INT]
+        ),
+    ) -> Series[_str]: ...
+    @overload
     def __rmul__(
         self: Series[T_INT], other: bool | Sequence[bool]
     ) -> Series[T_INT]: ...
@@ -2894,6 +2943,21 @@ class Series(IndexOpsMixin[S1], NDFrame):
         axis: AxisIndex | None = 0,
     ) -> Series[Timedelta]: ...
     @overload
+    def rmul(
+        self: Series[_str],
+        other: (
+            int
+            | Sequence[int]
+            | np_ndarray_bool
+            | np_ndarray_anyint
+            | Index[T_INT]
+            | Series[T_INT]
+        ),
+        level: Level | None = None,
+        fill_value: float | None = None,
+        axis: int = 0,
+    ) -> Series[_str]: ...
+    @overload
     def rmul(
         self: Series[T_INT],
         other: bool | Sequence[bool],
@@ -4556,7 +4620,7 @@ class Series(IndexOpsMixin[S1], NDFrame):
         **kwargs: Any,
     ) -> np_1darray: ...
     @overload
-    def to_numpy(  # pyrefly: ignore[bad-override]
+    def to_numpy(
         self: Series[Timestamp],
         dtype: type[np.datetime64] | None = None,
         copy: bool = False,
@@ -4572,7 +4636,7 @@ class Series(IndexOpsMixin[S1], NDFrame):
         **kwargs: Any,
     ) -> np_1darray[GenericT]: ...
     @overload
-    def to_numpy(  # pyrefly: ignore[bad-override]
+    def to_numpy(
         self: Series[Timedelta],
         dtype: type[np.timedelta64] | None = None,
         copy: bool = False,

pandas-stubs/core/window/ewm.pyi

@@ -51,7 +51,7 @@ class ExponentialMovingWindowGroupby(
 class OnlineExponentialMovingWindow(ExponentialMovingWindow[NDFrameT]):
     def reset(self) -> None: ...
     def aggregate(self, func, *args: Any, **kwargs: Any): ...
-    def std(self, bias: bool = False, *args: Any, **kwargs: Any): ...  # pyrefly: ignore
+    def std(self, bias: bool = False, *args: Any, **kwargs: Any): ...
     def corr(
         self,
         other: DataFrame | Series | None = None,
@@ -66,7 +66,7 @@ class OnlineExponentialMovingWindow(ExponentialMovingWindow[NDFrameT]):
         numeric_only: bool = False,
     ): ...
     def var(self, bias: bool = False, numeric_only: bool = False): ...
-    def mean(  # pyrefly: ignore
+    def mean(
         self,
         *args: Any,
         update: NDFrameT | None = ...,

tests/indexes/arithmetic/str/test_mul.py

@@ -0,0 +1,126 @@
+from datetime import (
+    datetime,
+    timedelta,
+)
+from typing import Any
+
+import numpy as np
+from numpy import typing as npt  # noqa: F401
+import pandas as pd
+import pytest
+from typing_extensions import (
+    Never,
+    assert_type,
+)
+
+from tests import (
+    TYPE_CHECKING_INVALID_USAGE,
+    check,
+)
+
+
+@pytest.fixture
+def left() -> "pd.Index[str]":
+    """left operand"""
+    lo = pd.Index(["1", "2", "3"])
+    return check(assert_type(lo, "pd.Index[str]"), pd.Index, str)
+
+
+def test_mul_py_scalar(left: "pd.Index[str]") -> None:
+    """Test pd.Index[str] * Python native scalars"""
+    b, i, f, c = True, 1, 1.0, 1j
+    s, d = datetime(2025, 9, 27), timedelta(seconds=1)
+
+    check(assert_type(left * b, "pd.Index[str]"), pd.Index, str)
+    check(assert_type(left * i, "pd.Index[str]"), pd.Index, str)
+    if TYPE_CHECKING_INVALID_USAGE:
+        _03 = left * f  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _04 = left * c  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _05 = left * s  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _06 = left * d  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+
+    check(assert_type(b * left, "pd.Index[str]"), pd.Index, str)
+    check(assert_type(i * left, "pd.Index[str]"), pd.Index, str)
+    if TYPE_CHECKING_INVALID_USAGE:
+        _13 = f * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _14 = c * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _15 = s * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _16 = d * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+
+
+def test_mul_py_sequence(left: "pd.Index[str]") -> None:
+    """Test pd.Index[str] * Python native sequences"""
+    b, i, f, c = [True, False, True], [2, 3, 5], [1.0, 2.0, 3.0], [1j, 1j, 4j]
+    s = [datetime(2025, 9, d) for d in (27, 28, 29)]
+    d = [timedelta(seconds=s + 1) for s in range(3)]
+
+    check(assert_type(left * b, "pd.Index[str]"), pd.Index, str)
+    check(assert_type(left * i, "pd.Index[str]"), pd.Index, str)
+    if TYPE_CHECKING_INVALID_USAGE:
+        _03 = left * f  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _04 = left * c  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _05 = left * s  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _06 = left * d  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+
+    check(assert_type(b * left, "pd.Index[str]"), pd.Index, str)
+    check(assert_type(i * left, "pd.Index[str]"), pd.Index, str)
+    if TYPE_CHECKING_INVALID_USAGE:
+        _13 = f * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _14 = c * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _15 = s * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _16 = d * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+
+
+def test_mul_numpy_array(left: "pd.Index[str]") -> None:
+    """Test pd.Index[str] * numpy arrays"""
+    b = np.array([True, False, True], np.bool_)
+    i = np.array([2, 3, 5], np.int64)
+    f = np.array([1.0, 2.0, 3.0], np.float64)
+    c = np.array([1.1j, 2.2j, 4.1j], np.complex128)
+    s = np.array([np.datetime64(f"2025-09-{d}") for d in (27, 28, 29)], np.datetime64)
+    d = np.array([np.timedelta64(s + 1, "s") for s in range(3)], np.timedelta64)
+
+    check(assert_type(left * b, "pd.Index[str]"), pd.Index, str)
+    check(assert_type(left * i, "pd.Index[str]"), pd.Index, str)
+    if TYPE_CHECKING_INVALID_USAGE:
+        assert_type(left * f, Never)
+        assert_type(left * c, Never)
+        assert_type(left * s, Never)
+        assert_type(left * d, Never)
+
+    # `numpy` typing gives the corresponding `ndarray`s in the static type
+    # checking, where our `__rmul__` cannot override. At runtime, they return
+    # `Index` with the correct element type.
+    check(assert_type(b * left, "npt.NDArray[np.bool_]"), pd.Index, str)
+    check(assert_type(i * left, "npt.NDArray[np.int64]"), pd.Index, str)
+    if TYPE_CHECKING_INVALID_USAGE:
+        assert_type(f * left, "npt.NDArray[np.float64]")
+        assert_type(c * left, "npt.NDArray[np.complex128]")
+        assert_type(s * left, Any)
+        assert_type(d * left, "npt.NDArray[np.timedelta64]")
+
+
+def test_mul_pd_index(left: "pd.Index[str]") -> None:
+    """Test pd.Index[str] * pandas Indexes"""
+    b = pd.Index([True, False, True])
+    i = pd.Index([2, 3, 5])
+    f = pd.Index([1.0, 2.0, 3.0])
+    c = pd.Index([1.1j, 2.2j, 4.1j])
+    s = pd.Index([datetime(2025, 9, d) for d in (27, 28, 29)])
+    d = pd.Index([timedelta(seconds=s + 1) for s in range(3)])
+
+    check(assert_type(left * b, "pd.Index[str]"), pd.Index, str)
+    check(assert_type(left * i, "pd.Index[str]"), pd.Index, str)
+    if TYPE_CHECKING_INVALID_USAGE:
+        _03 = left * f  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _04 = left * c  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _05 = left * s  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _06 = left * d  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+
+    check(assert_type(b * left, "pd.Index[str]"), pd.Index, str)
+    check(assert_type(i * left, "pd.Index[str]"), pd.Index, str)
+    if TYPE_CHECKING_INVALID_USAGE:
+        _13 = f * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _14 = c * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _15 = s * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]
+        _16 = d * left  # type: ignore[operator] # pyright: ignore[reportOperatorIssue]