diff --git a/py-polars/docs/source/conf.py b/py-polars/docs/source/conf.py
index 231da57375de..85a25283e51e 100644
--- a/py-polars/docs/source/conf.py
+++ b/py-polars/docs/source/conf.py
@@ -205,7 +205,7 @@ def linkcode_resolve(domain: str, info: dict[str, Any]) -> str | None:
                 # Accessing deprecated objects will generate noisy warnings
                 warnings.simplefilter("ignore", FutureWarning)
                 obj = getattr(obj, part)
-        except AttributeError:
+        except AttributeError:  # noqa: PERF203
             return None
 
     try:
diff --git a/py-polars/docs/source/reference/api.rst b/py-polars/docs/source/reference/api.rst
index 8cd9dc77475b..20eb4e0fa5cb 100644
--- a/py-polars/docs/source/reference/api.rst
+++ b/py-polars/docs/source/reference/api.rst
@@ -46,7 +46,7 @@ Examples
 
             @pl.api.register_expr_namespace("greetings")
             class Greetings:
-                def __init__(self, expr: pl.Expr):
+                def __init__(self, expr: pl.Expr) -> None:
                     self._expr = expr
 
                 def hello(self) -> pl.Expr:
@@ -80,7 +80,7 @@ Examples
 
             @pl.api.register_dataframe_namespace("split")
             class SplitFrame:
-                def __init__(self, df: pl.DataFrame):
+                def __init__(self, df: pl.DataFrame) -> None:
                     self._df = df
 
                 def by_alternate_rows(self) -> list[pl.DataFrame]:
@@ -112,7 +112,7 @@ Examples
 
             @pl.api.register_lazyframe_namespace("types")
             class DTypeOperations:
-                def __init__(self, ldf: pl.LazyFrame):
+                def __init__(self, ldf: pl.LazyFrame) -> None:
                     self._ldf = ldf
 
                 def upcast_integer_types(self) -> pl.LazyFrame:
@@ -145,7 +145,7 @@ Examples
 
             @pl.api.register_series_namespace("math")
             class MathShortcuts:
-                def __init__(self, s: pl.Series):
+                def __init__(self, s: pl.Series) -> None:
                     self._s = s
 
                 def square(self) -> pl.Series:
diff --git a/py-polars/polars/__init__.py b/py-polars/polars/__init__.py
index d7da45a84f75..10f0ee54228b 100644
--- a/py-polars/polars/__init__.py
+++ b/py-polars/polars/__init__.py
@@ -16,6 +16,8 @@
 
     __register_startup_deps()
 
+from typing import Any
+
 from polars import api, exceptions, plugins, selectors
 from polars._utils.polars_version import get_polars_version as _get_polars_version
 
@@ -380,7 +382,7 @@
 ]
 
 
-def __getattr__(name: str):  # type: ignore[no-untyped-def]
+def __getattr__(name: str) -> Any:
     # Deprecate re-export of exceptions at top-level
     if name in dir(exceptions):
         from polars._utils.deprecation import issue_deprecation_warning
diff --git a/py-polars/polars/_utils/async_.py b/py-polars/polars/_utils/async_.py
index 5669bdbb6790..a8fed8facda7 100644
--- a/py-polars/polars/_utils/async_.py
+++ b/py-polars/polars/_utils/async_.py
@@ -15,7 +15,7 @@
 
 
 class _GeventDataFrameResult(Generic[T]):
-    __slots__ = ("_watcher", "_value", "_result")
+    __slots__ = ("_result", "_value", "_watcher")
 
     def __init__(self) -> None:
         if not _GEVENT_AVAILABLE:
diff --git a/py-polars/polars/_utils/slice.py b/py-polars/polars/_utils/slice.py
index d22bf3c3bdbf..21ba5cf8a121 100644
--- a/py-polars/polars/_utils/slice.py
+++ b/py-polars/polars/_utils/slice.py
@@ -24,7 +24,7 @@ class PolarsSlice:
     is_unbounded: bool
     obj: FrameOrSeries
 
-    def __init__(self, obj: FrameOrSeries):
+    def __init__(self, obj: FrameOrSeries) -> None:
         self.obj = obj
 
     @staticmethod
@@ -116,7 +116,7 @@ class LazyPolarsSlice:
 
     obj: LazyFrame
 
-    def __init__(self, obj: LazyFrame):
+    def __init__(self, obj: LazyFrame) -> None:
         self.obj = obj
 
     def apply(self, s: slice) -> LazyFrame:
diff --git a/py-polars/polars/_utils/udfs.py b/py-polars/polars/_utils/udfs.py
index dca868fb9f9f..661c4e9cf303 100644
--- a/py-polars/polars/_utils/udfs.py
+++ b/py-polars/polars/_utils/udfs.py
@@ -330,7 +330,7 @@ class BytecodeParser:
     _map_target_name: str | None = None
     _caller_variables: dict[str, Any] | None = None
 
-    def __init__(self, function: Callable[[Any], Any], map_target: MapTarget):
+    def __init__(self, function: Callable[[Any], Any], map_target: MapTarget) -> None:
         """
         Initialize BytecodeParser instance and prepare to introspect UDFs.
 
@@ -745,7 +745,7 @@ def __init__(
         instructions: Iterator[Instruction],
         function: Callable[[Any], Any],
         caller_variables: dict[str, Any] | None,
-    ):
+    ) -> None:
         self._function = function
         self._caller_variables = caller_variables
         self._original_instructions = list(instructions)
diff --git a/py-polars/polars/_utils/various.py b/py-polars/polars/_utils/various.py
index f82bbec0d785..f25ab95e23c2 100644
--- a/py-polars/polars/_utils/various.py
+++ b/py-polars/polars/_utils/various.py
@@ -128,9 +128,8 @@ def is_sequence(
     val: object, *, include_series: bool = False
 ) -> TypeGuard[Sequence[Any]]:
     """Check whether the given input is a numpy array or python sequence."""
-    return (
-        (_check_for_numpy(val) and isinstance(val, np.ndarray))
-        or isinstance(val, (pl.Series, Sequence) if include_series else Sequence)
+    return (_check_for_numpy(val) and isinstance(val, np.ndarray)) or (
+        isinstance(val, (pl.Series, Sequence) if include_series else Sequence)
         and not isinstance(val, str)
     )
 
diff --git a/py-polars/polars/api.py b/py-polars/polars/api.py
index 84262d1b7998..11a61b63e570 100644
--- a/py-polars/polars/api.py
+++ b/py-polars/polars/api.py
@@ -11,8 +11,8 @@
 
 
 __all__ = [
-    "register_expr_namespace",
     "register_dataframe_namespace",
+    "register_expr_namespace",
     "register_lazyframe_namespace",
     "register_series_namespace",
 ]
@@ -84,7 +84,7 @@ def register_expr_namespace(name: str) -> Callable[[type[NS]], type[NS]]:
     --------
     >>> @pl.api.register_expr_namespace("pow_n")
     ... class PowersOfN:
-    ...     def __init__(self, expr: pl.Expr):
+    ...     def __init__(self, expr: pl.Expr) -> None:
     ...         self._expr = expr
     ...
     ...     def next(self, p: int) -> pl.Expr:
@@ -137,7 +137,7 @@ def register_dataframe_namespace(name: str) -> Callable[[type[NS]], type[NS]]:
     --------
     >>> @pl.api.register_dataframe_namespace("split")
     ... class SplitFrame:
-    ...     def __init__(self, df: pl.DataFrame):
+    ...     def __init__(self, df: pl.DataFrame) -> None:
     ...         self._df = df
     ...
     ...     def by_first_letter_of_column_names(self) -> list[pl.DataFrame]:
@@ -235,7 +235,7 @@ def register_lazyframe_namespace(name: str) -> Callable[[type[NS]], type[NS]]:
     --------
     >>> @pl.api.register_lazyframe_namespace("types")
     ... class DTypeOperations:
-    ...     def __init__(self, lf: pl.LazyFrame):
+    ...     def __init__(self, lf: pl.LazyFrame) -> None:
     ...         self._lf = lf
     ...
     ...     def split_by_column_dtypes(self) -> list[pl.LazyFrame]:
@@ -336,7 +336,7 @@ def register_series_namespace(name: str) -> Callable[[type[NS]], type[NS]]:
     --------
     >>> @pl.api.register_series_namespace("math")
     ... class MathShortcuts:
-    ...     def __init__(self, s: pl.Series):
+    ...     def __init__(self, s: pl.Series) -> None:
     ...         self._s = s
     ...
     ...     def square(self) -> pl.Series:
diff --git a/py-polars/polars/config.py b/py-polars/polars/config.py
index e2f7f27292d2..0ad1dfb985f9 100644
--- a/py-polars/polars/config.py
+++ b/py-polars/polars/config.py
@@ -19,6 +19,12 @@
     else:
         from typing_extensions import TypeAlias
 
+    if sys.version_info >= (3, 11):
+        from typing import Self
+    else:
+        from typing_extensions import Self
+
+
 __all__ = ["Config"]
 
 TableFormatNames: TypeAlias = Literal[
@@ -160,7 +166,7 @@ def __init__(self, *, restore_defaults: bool = False, **options: Any) -> None:
                 raise AttributeError(msg)
             getattr(self, opt)(value)
 
-    def __enter__(self) -> Config:
+    def __enter__(self) -> Self:
         """Support setting temporary Config options that are reset on scope exit."""
         self._original_state = self._original_state or self.save()
         return self
diff --git a/py-polars/polars/dataframe/_html.py b/py-polars/polars/dataframe/_html.py
index 64c0847f250e..62464873e42a 100644
--- a/py-polars/polars/dataframe/_html.py
+++ b/py-polars/polars/dataframe/_html.py
@@ -22,7 +22,7 @@ def __init__(
         elements: list[str],
         tag: str,
         attributes: dict[str, str] | None = None,
-    ):
+    ) -> None:
         self.tag = tag
         self.elements = elements
         self.attributes = attributes
@@ -54,7 +54,7 @@ def __init__(
         max_cols: int = 75,
         max_rows: int = 40,
         from_series: bool = False,
-    ):
+    ) -> None:
         self.df = df
         self.elements: list[str] = []
         self.max_cols = max_cols
diff --git a/py-polars/polars/dataframe/frame.py b/py-polars/polars/dataframe/frame.py
index c422f8bffdf8..d9faf3e7cde8 100644
--- a/py-polars/polars/dataframe/frame.py
+++ b/py-polars/polars/dataframe/frame.py
@@ -351,7 +351,7 @@ def __init__(
         orient: Orientation | None = None,
         infer_schema_length: int | None = N_INFER_DEFAULT,
         nan_to_null: bool = False,
-    ):
+    ) -> None:
         if data is None:
             self._df = dict_to_pydf(
                 {}, schema=schema, schema_overrides=schema_overrides
@@ -1106,10 +1106,10 @@ def __bool__(self) -> NoReturn:
         )
         raise TypeError(msg)
 
-    def __eq__(self, other: Any) -> DataFrame:  # type: ignore[override]
+    def __eq__(self, other: object) -> DataFrame:  # type: ignore[override]
         return self._comp(other, "eq")
 
-    def __ne__(self, other: Any) -> DataFrame:  # type: ignore[override]
+    def __ne__(self, other: object) -> DataFrame:  # type: ignore[override]
         return self._comp(other, "neq")
 
     def __gt__(self, other: Any) -> DataFrame:
@@ -3428,7 +3428,7 @@ def write_excel(
             hidden_columns = ()
         hidden_columns = _expand_selectors(df, hidden_columns)
         if isinstance(column_widths, int):
-            column_widths = {column: column_widths for column in df.columns}
+            column_widths = dict.fromkeys(df.columns, column_widths)
         else:
             column_widths = _expand_selector_dicts(  # type: ignore[assignment]
                 df, column_widths, expand_keys=True, expand_values=False
@@ -3740,10 +3740,8 @@ def write_parquet(
         if compression is None:
             compression = "uncompressed"
         if isinstance(file, (str, Path)):
-            if (
-                partition_by is not None
-                or pyarrow_options is not None
-                and pyarrow_options.get("partition_cols")
+            if partition_by is not None or (
+                pyarrow_options is not None and pyarrow_options.get("partition_cols")
             ):
                 file = normalize_filepath(file, check_not_directory=False)
             else:
@@ -5999,7 +5997,7 @@ def group_by(
         │ c   ┆ 3   ┆ 1   │
         └─────┴─────┴─────┘
         """
-        for _key, value in named_by.items():
+        for value in named_by.values():
             if not isinstance(value, (str, pl.Expr, pl.Series)):
                 msg = (
                     f"Expected Polars expression or object convertible to one, got {type(value)}.\n\n"
diff --git a/py-polars/polars/dataframe/group_by.py b/py-polars/polars/dataframe/group_by.py
index f3a9c185de41..204afc3d25c1 100644
--- a/py-polars/polars/dataframe/group_by.py
+++ b/py-polars/polars/dataframe/group_by.py
@@ -35,7 +35,7 @@ def __init__(
         *by: IntoExpr | Iterable[IntoExpr],
         maintain_order: bool,
         **named_by: IntoExpr,
-    ):
+    ) -> None:
         """
         Utility class for performing a group by operation over the given DataFrame.
 
@@ -772,7 +772,7 @@ def __init__(
         offset: str | timedelta | None,
         closed: ClosedInterval,
         group_by: IntoExpr | Iterable[IntoExpr] | None,
-    ):
+    ) -> None:
         period = parse_as_duration_string(period)
         offset = parse_as_duration_string(offset)
 
@@ -909,7 +909,7 @@ def __init__(
         label: Label,
         group_by: IntoExpr | Iterable[IntoExpr] | None,
         start_by: StartBy,
-    ):
+    ) -> None:
         every = parse_as_duration_string(every)
         period = parse_as_duration_string(period)
         offset = parse_as_duration_string(offset)
diff --git a/py-polars/polars/datatypes/classes.py b/py-polars/polars/datatypes/classes.py
index b815d7d17608..8906f2459c28 100644
--- a/py-polars/polars/datatypes/classes.py
+++ b/py-polars/polars/datatypes/classes.py
@@ -325,7 +325,7 @@ def __init__(
         self,
         precision: int | None = None,
         scale: int = 0,
-    ):
+    ) -> None:
         # Issuing the warning on `__init__` does not trigger when the class is used
         # without being instantiated, but it's better than nothing
         from polars._utils.unstable import issue_unstable_warning
@@ -422,7 +422,7 @@ class Datetime(TemporalType):
 
     def __init__(
         self, time_unit: TimeUnit = "us", time_zone: str | timezone | None = None
-    ):
+    ) -> None:
         if time_unit not in ("ms", "us", "ns"):
             msg = (
                 "invalid `time_unit`"
@@ -475,7 +475,7 @@ class Duration(TemporalType):
 
     time_unit: TimeUnit
 
-    def __init__(self, time_unit: TimeUnit = "us"):
+    def __init__(self, time_unit: TimeUnit = "us") -> None:
         if time_unit not in ("ms", "us", "ns"):
             msg = (
                 "invalid `time_unit`"
@@ -518,7 +518,7 @@ class Categorical(DataType):
     def __init__(
         self,
         ordering: CategoricalOrdering | None = "physical",
-    ):
+    ) -> None:
         self.ordering = ordering
 
     def __repr__(self) -> str:
@@ -554,7 +554,7 @@ class Enum(DataType):
 
     categories: Series
 
-    def __init__(self, categories: Series | Iterable[str]):
+    def __init__(self, categories: Series | Iterable[str]) -> None:
         # Issuing the warning on `__init__` does not trigger when the class is used
         # without being instantiated, but it's better than nothing
         from polars._utils.unstable import issue_unstable_warning
@@ -654,7 +654,7 @@ class List(NestedType):
 
     inner: PolarsDataType
 
-    def __init__(self, inner: PolarsDataType | PythonDataType):
+    def __init__(self, inner: PolarsDataType | PythonDataType) -> None:
         self.inner = polars.datatypes.parse_into_dtype(inner)
 
     def __eq__(self, other: PolarsDataType) -> bool:  # type: ignore[override]
@@ -713,7 +713,7 @@ def __init__(
         shape: int | tuple[int, ...] | None = None,
         *,
         width: int | None = None,
-    ):
+    ) -> None:
         if width is not None:
             from polars._utils.deprecation import issue_deprecation_warning
 
@@ -803,7 +803,7 @@ class Field:
     name: str
     dtype: PolarsDataType
 
-    def __init__(self, name: str, dtype: PolarsDataType):
+    def __init__(self, name: str, dtype: PolarsDataType) -> None:
         self.name = name
         self.dtype = polars.datatypes.parse_into_dtype(dtype)
 
@@ -858,7 +858,7 @@ class Struct(NestedType):
 
     fields: list[Field]
 
-    def __init__(self, fields: Sequence[Field] | SchemaDict):
+    def __init__(self, fields: Sequence[Field] | SchemaDict) -> None:
         if isinstance(fields, Mapping):
             self.fields = [Field(name, dtype) for name, dtype in fields.items()]
         else:
diff --git a/py-polars/polars/datatypes/convert.py b/py-polars/polars/datatypes/convert.py
index 1b0806b2ea75..91fe61da4b6f 100644
--- a/py-polars/polars/datatypes/convert.py
+++ b/py-polars/polars/datatypes/convert.py
@@ -318,7 +318,7 @@ def numpy_char_code_to_dtype(dtype_char: str) -> PolarsDataType:
         return Binary
     try:
         return DataTypeMappings.NUMPY_KIND_AND_ITEMSIZE_TO_DTYPE[
-            (dtype.kind, dtype.itemsize)
+            dtype.kind, dtype.itemsize
         ]
     except KeyError:  # pragma: no cover
         msg = f"cannot parse numpy data type {dtype!r} into Polars data type"
diff --git a/py-polars/polars/datatypes/group.py b/py-polars/polars/datatypes/group.py
index 1cf67c7eba22..f30153ed6e7a 100644
--- a/py-polars/polars/datatypes/group.py
+++ b/py-polars/polars/datatypes/group.py
@@ -26,12 +26,19 @@
 )
 
 if TYPE_CHECKING:
+    import sys
+
     from polars._typing import (
         PolarsDataType,
         PolarsIntegerType,
         PolarsTemporalType,
     )
 
+    if sys.version_info >= (3, 11):
+        from typing import Self
+    else:
+        from typing_extensions import Self
+
 
 class DataTypeGroup(frozenset):  # type: ignore[type-arg]
     """Group of data types."""
@@ -40,7 +47,7 @@ class DataTypeGroup(frozenset):  # type: ignore[type-arg]
 
     def __new__(
         cls, items: Iterable[DataType | DataTypeClass], *, match_base_type: bool = True
-    ) -> DataTypeGroup:
+    ) -> Self:
         """
         Construct a DataTypeGroup.
 
diff --git a/py-polars/polars/expr/array.py b/py-polars/polars/expr/array.py
index 98b8dfe80541..302b0b024adf 100644
--- a/py-polars/polars/expr/array.py
+++ b/py-polars/polars/expr/array.py
@@ -17,7 +17,7 @@ class ExprArrayNameSpace:
 
     _accessor = "arr"
 
-    def __init__(self, expr: Expr):
+    def __init__(self, expr: Expr) -> None:
         self._pyexpr = expr._pyexpr
 
     def min(self) -> Expr:
diff --git a/py-polars/polars/expr/binary.py b/py-polars/polars/expr/binary.py
index 7ea6dc4d79ea..62cf43180fd3 100644
--- a/py-polars/polars/expr/binary.py
+++ b/py-polars/polars/expr/binary.py
@@ -16,7 +16,7 @@ class ExprBinaryNameSpace:
 
     _accessor = "bin"
 
-    def __init__(self, expr: Expr):
+    def __init__(self, expr: Expr) -> None:
         self._pyexpr = expr._pyexpr
 
     def contains(self, literal: IntoExpr) -> Expr:
diff --git a/py-polars/polars/expr/categorical.py b/py-polars/polars/expr/categorical.py
index 2d6ce7646443..fed977c3644d 100644
--- a/py-polars/polars/expr/categorical.py
+++ b/py-polars/polars/expr/categorical.py
@@ -13,7 +13,7 @@ class ExprCatNameSpace:
 
     _accessor = "cat"
 
-    def __init__(self, expr: Expr):
+    def __init__(self, expr: Expr) -> None:
         self._pyexpr = expr._pyexpr
 
     def get_categories(self) -> Expr:
diff --git a/py-polars/polars/expr/datetime.py b/py-polars/polars/expr/datetime.py
index 9a03b46b12d3..a35674412ccf 100644
--- a/py-polars/polars/expr/datetime.py
+++ b/py-polars/polars/expr/datetime.py
@@ -30,7 +30,7 @@ class ExprDateTimeNameSpace:
 
     _accessor = "dt"
 
-    def __init__(self, expr: Expr):
+    def __init__(self, expr: Expr) -> None:
         self._pyexpr = expr._pyexpr
 
     def add_business_days(
diff --git a/py-polars/polars/expr/expr.py b/py-polars/polars/expr/expr.py
index d94b257b0f1b..bb2430671234 100644
--- a/py-polars/polars/expr/expr.py
+++ b/py-polars/polars/expr/expr.py
@@ -2540,10 +2540,8 @@ def gather(
         │ two   ┆ [4, 99]   │
         └───────┴───────────┘
         """
-        if (
-            isinstance(indices, Sequence)
-            and not isinstance(indices, str)
-            or (_check_for_numpy(indices) and isinstance(indices, np.ndarray))
+        if (isinstance(indices, Sequence) and not isinstance(indices, str)) or (
+            _check_for_numpy(indices) and isinstance(indices, np.ndarray)
         ):
             indices_lit = F.lit(pl.Series("", indices, dtype=Int64))._pyexpr
         else:
@@ -4260,7 +4258,7 @@ def __init__(
             self,
             function: Callable[[Series], Series | Any],
             return_dtype: PolarsDataType | None,
-        ):
+        ) -> None:
             self.function = function
             self.return_dtype = return_dtype
 
diff --git a/py-polars/polars/expr/list.py b/py-polars/polars/expr/list.py
index 5655b58c86cb..5560f368767b 100644
--- a/py-polars/polars/expr/list.py
+++ b/py-polars/polars/expr/list.py
@@ -25,7 +25,7 @@ class ExprListNameSpace:
 
     _accessor = "list"
 
-    def __init__(self, expr: Expr):
+    def __init__(self, expr: Expr) -> None:
         self._pyexpr = expr._pyexpr
 
     def __getitem__(self, item: int) -> Expr:
diff --git a/py-polars/polars/expr/meta.py b/py-polars/polars/expr/meta.py
index 333b35351a2d..a3536c97711e 100644
--- a/py-polars/polars/expr/meta.py
+++ b/py-polars/polars/expr/meta.py
@@ -20,7 +20,7 @@ class ExprMetaNameSpace:
 
     _accessor = "meta"
 
-    def __init__(self, expr: Expr):
+    def __init__(self, expr: Expr) -> None:
         self._pyexpr = expr._pyexpr
 
     def __eq__(self, other: ExprMetaNameSpace | Expr) -> bool:  # type: ignore[override]
diff --git a/py-polars/polars/expr/name.py b/py-polars/polars/expr/name.py
index 8b6fe24d8dea..0b53cd158cab 100644
--- a/py-polars/polars/expr/name.py
+++ b/py-polars/polars/expr/name.py
@@ -11,7 +11,7 @@ class ExprNameNameSpace:
 
     _accessor = "name"
 
-    def __init__(self, expr: Expr):
+    def __init__(self, expr: Expr) -> None:
         self._from_pyexpr = expr._from_pyexpr
         self._pyexpr = expr._pyexpr
 
diff --git a/py-polars/polars/expr/string.py b/py-polars/polars/expr/string.py
index 351c1cdd8565..1b04ab7febad 100644
--- a/py-polars/polars/expr/string.py
+++ b/py-polars/polars/expr/string.py
@@ -36,7 +36,7 @@ class ExprStringNameSpace:
 
     _accessor = "str"
 
-    def __init__(self, expr: Expr):
+    def __init__(self, expr: Expr) -> None:
         self._pyexpr = expr._pyexpr
 
     def to_date(
diff --git a/py-polars/polars/expr/struct.py b/py-polars/polars/expr/struct.py
index 225f82b67199..09b9c1688fbb 100644
--- a/py-polars/polars/expr/struct.py
+++ b/py-polars/polars/expr/struct.py
@@ -16,7 +16,7 @@ class ExprStructNameSpace:
 
     _accessor = "struct"
 
-    def __init__(self, expr: Expr):
+    def __init__(self, expr: Expr) -> None:
         self._pyexpr = expr._pyexpr
 
     def __getitem__(self, item: str | int) -> Expr:
diff --git a/py-polars/polars/expr/whenthen.py b/py-polars/polars/expr/whenthen.py
index 1467d9e73698..752ed1b44c06 100644
--- a/py-polars/polars/expr/whenthen.py
+++ b/py-polars/polars/expr/whenthen.py
@@ -24,7 +24,7 @@ class When:
     In this state, `then` must be called to continue to finish the expression.
     """
 
-    def __init__(self, when: Any):
+    def __init__(self, when: Any) -> None:
         self._when = when
 
     def then(self, statement: IntoExpr) -> Then:
@@ -49,7 +49,7 @@ class Then(Expr):
     Represents the state of the expression after `pl.when(...).then(...)` is called.
     """
 
-    def __init__(self, then: Any):
+    def __init__(self, then: Any) -> None:
         self._then = then
 
     @classmethod
@@ -108,7 +108,7 @@ class ChainedWhen:
     In this state, `then` must be called to continue to finish the expression.
     """
 
-    def __init__(self, chained_when: Any):
+    def __init__(self, chained_when: Any) -> None:
         self._chained_when = chained_when
 
     def then(self, statement: IntoExpr) -> ChainedThen:
@@ -133,7 +133,7 @@ class ChainedThen(Expr):
     Represents the state of the expression after an additional `then` is called.
     """
 
-    def __init__(self, chained_then: Any):
+    def __init__(self, chained_then: Any) -> None:
         self._chained_then = chained_then
 
     @classmethod
diff --git a/py-polars/polars/functions/aggregation/__init__.py b/py-polars/polars/functions/aggregation/__init__.py
index 245b458dfdc7..9dcd4f9b268b 100644
--- a/py-polars/polars/functions/aggregation/__init__.py
+++ b/py-polars/polars/functions/aggregation/__init__.py
@@ -18,16 +18,16 @@
 
 __all__ = [
     "all",
-    "any",
-    "cum_sum",
-    "max",
-    "min",
-    "sum",
     "all_horizontal",
+    "any",
     "any_horizontal",
+    "cum_sum",
     "cum_sum_horizontal",
+    "max",
     "max_horizontal",
     "mean_horizontal",
+    "min",
     "min_horizontal",
+    "sum",
     "sum_horizontal",
 ]
diff --git a/py-polars/polars/interchange/buffer.py b/py-polars/polars/interchange/buffer.py
index cd4981901d4c..2f3598169777 100644
--- a/py-polars/polars/interchange/buffer.py
+++ b/py-polars/polars/interchange/buffer.py
@@ -29,7 +29,7 @@ class PolarsBuffer(Buffer):
         a RuntimeError will be raised if data would be copied.
     """
 
-    def __init__(self, data: Series, *, allow_copy: bool = True):
+    def __init__(self, data: Series, *, allow_copy: bool = True) -> None:
         if data.n_chunks() > 1:
             if not allow_copy:
                 msg = "non-contiguous buffer must be made contiguous"
diff --git a/py-polars/polars/interchange/column.py b/py-polars/polars/interchange/column.py
index 197a8b5da584..65bc9a19fd46 100644
--- a/py-polars/polars/interchange/column.py
+++ b/py-polars/polars/interchange/column.py
@@ -34,7 +34,7 @@ class PolarsColumn(Column):
         a RuntimeError will be raised if data would be copied.
     """
 
-    def __init__(self, column: Series, *, allow_copy: bool = True):
+    def __init__(self, column: Series, *, allow_copy: bool = True) -> None:
         self._col = column
         self._allow_copy = allow_copy
 
diff --git a/py-polars/polars/interchange/dataframe.py b/py-polars/polars/interchange/dataframe.py
index 0fc6e5094e7d..c63af632c816 100644
--- a/py-polars/polars/interchange/dataframe.py
+++ b/py-polars/polars/interchange/dataframe.py
@@ -30,7 +30,7 @@ class PolarsDataFrame(InterchangeDataFrame):
 
     version = 0
 
-    def __init__(self, df: DataFrame, *, allow_copy: bool = True):
+    def __init__(self, df: DataFrame, *, allow_copy: bool = True) -> None:
         self._df = df
         self._allow_copy = allow_copy
 
diff --git a/py-polars/polars/io/csv/batched_reader.py b/py-polars/polars/io/csv/batched_reader.py
index f13efb7aa3b3..2bbb1583317c 100644
--- a/py-polars/polars/io/csv/batched_reader.py
+++ b/py-polars/polars/io/csv/batched_reader.py
@@ -56,7 +56,7 @@ def __init__(
         raise_if_empty: bool = True,
         truncate_ragged_lines: bool = False,
         decimal_comma: bool = False,
-    ):
+    ) -> None:
         path = normalize_filepath(source, check_not_directory=False)
 
         dtype_list: Sequence[tuple[str, PolarsDataType]] | None = None
diff --git a/py-polars/polars/io/database/_executor.py b/py-polars/polars/io/database/_executor.py
index bb56d48c6b2f..b45301b87da2 100644
--- a/py-polars/polars/io/database/_executor.py
+++ b/py-polars/polars/io/database/_executor.py
@@ -22,6 +22,7 @@
 
 if TYPE_CHECKING:
     import sys
+    from collections.abc import Iterator
     from types import TracebackType
 
     import pyarrow as pa
@@ -70,7 +71,7 @@ def __init__(self, frames: Any, *, cursor: Cursor) -> None:
         self._iter_frames = frames
         self._cursor = cursor
 
-    def __iter__(self) -> Iterable[DataFrame]:
+    def __iter__(self) -> Iterator[DataFrame]:
         yield from self._iter_frames
 
         if hasattr(self._cursor, "close"):
@@ -546,7 +547,7 @@ def to_polars(
                 if defer_cursor_close:
                     frame = (
                         df
-                        for df in CloseAfterFrameIter(  # type: ignore[attr-defined]
+                        for df in CloseAfterFrameIter(
                             frame,
                             cursor=self.result,
                         )
diff --git a/py-polars/polars/io/delta.py b/py-polars/polars/io/delta.py
index 66e60b723abb..9cb621fc5534 100644
--- a/py-polars/polars/io/delta.py
+++ b/py-polars/polars/io/delta.py
@@ -337,7 +337,7 @@ def _get_delta_lake_table(
 
 def _check_if_delta_available() -> None:
     if not _DELTALAKE_AVAILABLE:
-        msg = "deltalake is not installed" "\n\nPlease run: pip install deltalake"
+        msg = "deltalake is not installed\n\nPlease run: pip install deltalake"
         raise ModuleNotFoundError(msg)
 
 
diff --git a/py-polars/polars/io/ipc/__init__.py b/py-polars/polars/io/ipc/__init__.py
index 9423bbceb829..98f850931501 100644
--- a/py-polars/polars/io/ipc/__init__.py
+++ b/py-polars/polars/io/ipc/__init__.py
@@ -2,7 +2,7 @@
 
 __all__ = [
     "read_ipc",
-    "read_ipc_stream",
     "read_ipc_schema",
+    "read_ipc_stream",
     "scan_ipc",
 ]
diff --git a/py-polars/polars/io/ndjson.py b/py-polars/polars/io/ndjson.py
index cd9ea92bf3c0..33e85914ce34 100644
--- a/py-polars/polars/io/ndjson.py
+++ b/py-polars/polars/io/ndjson.py
@@ -122,9 +122,11 @@ def read_ndjson(
     """
     if not (
         isinstance(source, (str, Path))
-        or isinstance(source, Sequence)
-        and source
-        and isinstance(source[0], (str, Path))
+        or (
+            isinstance(source, Sequence)
+            and source
+            and isinstance(source[0], (str, Path))
+        )
     ):
         # TODO: A lot of the parameters aren't applied for BytesIO
         if isinstance(source, StringIO):
@@ -174,8 +176,7 @@ def scan_ndjson(
     | list[str]
     | list[Path]
     | list[IO[str]]
-    | list[IO[bytes]]
-    | bytes,
+    | list[IO[bytes]],
     *,
     schema: SchemaDefinition | None = None,
     schema_overrides: SchemaDefinition | None = None,
diff --git a/py-polars/polars/io/spreadsheet/_write_utils.py b/py-polars/polars/io/spreadsheet/_write_utils.py
index db947e6ef17d..ba4032f5293f 100644
--- a/py-polars/polars/io/spreadsheet/_write_utils.py
+++ b/py-polars/polars/io/spreadsheet/_write_utils.py
@@ -55,7 +55,7 @@ def _cluster(iterable: Iterable[Any], n: int = 2) -> Iterable[Any]:
 class _XLFormatCache:
     """Create/cache only one Format object per distinct set of format options."""
 
-    def __init__(self, wb: Workbook):
+    def __init__(self, wb: Workbook) -> None:
         self._cache: dict[str, Format] = {}
         self.wb = wb
 
@@ -412,10 +412,10 @@ def _map_str(s: Series) -> Series:
 
     # expand/normalise column totals
     if column_totals is True:
-        column_totals = {numeric(): "sum", **{t: "sum" for t in row_totals or ()}}
+        column_totals = {numeric(): "sum", **dict.fromkeys(row_totals or (), "sum")}
     elif isinstance(column_totals, str):
         fn = column_totals.lower()
-        column_totals = {numeric(): fn, **{t: fn for t in row_totals or ()}}
+        column_totals = {numeric(): fn, **dict.fromkeys(row_totals or (), fn)}
 
     column_totals = _unpack_multi_column_dict(  # type: ignore[assignment]
         _expand_selector_dicts(df, column_totals, expand_keys=True, expand_values=False)
@@ -423,7 +423,7 @@ def _map_str(s: Series) -> Series:
         else _expand_selectors(df, column_totals)
     )
     column_total_funcs = (
-        {col: "sum" for col in column_totals}
+        dict.fromkeys(column_totals, "sum")
         if isinstance(column_totals, Sequence)
         else (column_totals.copy() if isinstance(column_totals, dict) else {})
     )
diff --git a/py-polars/polars/io/spreadsheet/functions.py b/py-polars/polars/io/spreadsheet/functions.py
index 1fd25cc1417a..dd445f9e9c97 100644
--- a/py-polars/polars/io/spreadsheet/functions.py
+++ b/py-polars/polars/io/spreadsheet/functions.py
@@ -927,7 +927,7 @@ def _read_spreadsheet_calamine(
     schema_overrides = schema_overrides or {}
     if read_options.get("schema_sample_rows") == 0:
         # ref: https://github.com/ToucanToco/fastexcel/issues/236
-        read_options["dtypes"] = {idx: "string" for idx in range(16384)}
+        read_options["dtypes"] = dict.fromkeys(range(16384), "string")
     elif schema_overrides and fastexcel_version >= (0, 10):
         parser_dtypes = read_options.get("dtypes", {})
         for name, dtype in schema_overrides.items():
diff --git a/py-polars/polars/lazyframe/frame.py b/py-polars/polars/lazyframe/frame.py
index 0eb14cba9e88..f1db322e4460 100644
--- a/py-polars/polars/lazyframe/frame.py
+++ b/py-polars/polars/lazyframe/frame.py
@@ -302,7 +302,7 @@ def __init__(
         orient: Orientation | None = None,
         infer_schema_length: int | None = N_INFER_DEFAULT,
         nan_to_null: bool = False,
-    ):
+    ) -> None:
         from polars.dataframe import DataFrame
 
         self._ldf = (
@@ -585,10 +585,10 @@ def _comparison_error(self, operator: str) -> NoReturn:
         msg = f'"{operator!r}" comparison not supported for LazyFrame objects'
         raise TypeError(msg)
 
-    def __eq__(self, other: Any) -> NoReturn:
+    def __eq__(self, other: object) -> NoReturn:
         self._comparison_error("==")
 
-    def __ne__(self, other: Any) -> NoReturn:
+    def __ne__(self, other: object) -> NoReturn:
         self._comparison_error("!=")
 
     def __gt__(self, other: Any) -> NoReturn:
@@ -1733,7 +1733,7 @@ def profile(
             )
             import matplotlib.pyplot as plt
 
-            fig, ax = plt.subplots(1, figsize=figsize)
+            _fig, ax = plt.subplots(1, figsize=figsize)
 
             max_val = timings["end"][-1]
             timings_ = timings.reverse()
@@ -2970,7 +2970,7 @@ def cast(
             cast_map.update(
                 {c: dtype}
                 if isinstance(c, str)
-                else {x: dtype for x in expand_selector(self, c)}  # type: ignore[arg-type]
+                else dict.fromkeys(expand_selector(self, c), dtype)  # type: ignore[arg-type]
             )
 
         return self._from_pyldf(self._ldf.cast(cast_map, strict))
@@ -3498,7 +3498,7 @@ def group_by(
         │ c   ┆ 1   ┆ 1.0 │
         └─────┴─────┴─────┘
         """
-        for _key, value in named_by.items():
+        for value in named_by.values():
             if not isinstance(value, (str, pl.Expr, pl.Series)):
                 msg = (
                     f"Expected Polars expression or object convertible to one, got {type(value)}.\n\n"
diff --git a/py-polars/polars/ml/torch.py b/py-polars/polars/ml/torch.py
index c8c80c0c9581..134e1c260e63 100644
--- a/py-polars/polars/ml/torch.py
+++ b/py-polars/polars/ml/torch.py
@@ -121,7 +121,7 @@ def __init__(
         *,
         label: str | Expr | Sequence[str | Expr] | None = None,
         features: str | Expr | Sequence[str | Expr] | None = None,
-    ):
+    ) -> None:
         issue_unstable_warning("`PolarsDataset` is considered unstable.")
         if isinstance(label, (str, Expr)):
             label = [label]
diff --git a/py-polars/polars/schema.py b/py-polars/polars/schema.py
index 019d2d2f3ad0..a099b67aac2c 100644
--- a/py-polars/polars/schema.py
+++ b/py-polars/polars/schema.py
@@ -58,7 +58,7 @@ def __init__(
             | Iterable[tuple[str, DataType | PythonDataType]]
             | None
         ) = None,
-    ):
+    ) -> None:
         input = (
             schema.items() if schema and isinstance(schema, Mapping) else (schema or {})
         )
diff --git a/py-polars/polars/selectors.py b/py-polars/polars/selectors.py
index 2e56aa3fb91e..36b26068a77f 100644
--- a/py-polars/polars/selectors.py
+++ b/py-polars/polars/selectors.py
@@ -248,7 +248,7 @@ def _expand_selector_dicts(
             if tuple_keys:
                 expanded[cols] = value
             else:
-                expanded.update({c: value for c in cols})
+                expanded.update(dict.fromkeys(cols, value))
         else:
             expanded[key] = value
     return expanded
@@ -319,7 +319,7 @@ def __init__(
         expr: Expr,
         name: str,
         parameters: dict[str, Any] | None = None,
-    ):
+    ) -> None:
         self._pyexpr = expr._pyexpr
         self._attrs = {
             "params": parameters,
diff --git a/py-polars/polars/series/array.py b/py-polars/polars/series/array.py
index 75910ad9446c..3051228ca941 100644
--- a/py-polars/polars/series/array.py
+++ b/py-polars/polars/series/array.py
@@ -20,7 +20,7 @@ class ArrayNameSpace:
 
     _accessor = "arr"
 
-    def __init__(self, series: Series):
+    def __init__(self, series: Series) -> None:
         self._s: PySeries = series._s
 
     def min(self) -> Series:
diff --git a/py-polars/polars/series/binary.py b/py-polars/polars/series/binary.py
index ded8ed5a0c8a..a1cdf5d8fb80 100644
--- a/py-polars/polars/series/binary.py
+++ b/py-polars/polars/series/binary.py
@@ -16,7 +16,7 @@ class BinaryNameSpace:
 
     _accessor = "bin"
 
-    def __init__(self, series: Series):
+    def __init__(self, series: Series) -> None:
         self._s: PySeries = series._s
 
     def contains(self, literal: IntoExpr) -> Series:
diff --git a/py-polars/polars/series/categorical.py b/py-polars/polars/series/categorical.py
index 82641bd41c83..04620b5ada9b 100644
--- a/py-polars/polars/series/categorical.py
+++ b/py-polars/polars/series/categorical.py
@@ -17,7 +17,7 @@ class CatNameSpace:
 
     _accessor = "cat"
 
-    def __init__(self, series: Series):
+    def __init__(self, series: Series) -> None:
         self._s: PySeries = series._s
 
     def get_categories(self) -> Series:
diff --git a/py-polars/polars/series/datetime.py b/py-polars/polars/series/datetime.py
index 928c81410a62..e4da43de78c7 100644
--- a/py-polars/polars/series/datetime.py
+++ b/py-polars/polars/series/datetime.py
@@ -30,7 +30,7 @@ class DateTimeNameSpace:
 
     _accessor = "dt"
 
-    def __init__(self, series: Series):
+    def __init__(self, series: Series) -> None:
         self._s: PySeries = series._s
 
     def __getitem__(self, item: int) -> dt.date | dt.datetime | dt.timedelta:
diff --git a/py-polars/polars/series/list.py b/py-polars/polars/series/list.py
index 53bcb22ce6f3..c6480e3ddbff 100644
--- a/py-polars/polars/series/list.py
+++ b/py-polars/polars/series/list.py
@@ -25,7 +25,7 @@ class ListNameSpace:
 
     _accessor = "list"
 
-    def __init__(self, series: Series):
+    def __init__(self, series: Series) -> None:
         self._s: PySeries = series._s
 
     def all(self) -> Series:
diff --git a/py-polars/polars/series/series.py b/py-polars/polars/series/series.py
index e2a4cb936e47..532cd4c74bc1 100644
--- a/py-polars/polars/series/series.py
+++ b/py-polars/polars/series/series.py
@@ -267,7 +267,7 @@ def __init__(
         *,
         strict: bool = True,
         nan_to_null: bool = False,
-    ):
+    ) -> None:
         # If 'Unknown' treat as None to trigger type inference
         if dtype == Unknown:
             dtype = None
@@ -761,24 +761,24 @@ def _comp(self, other: Any, op: ComparisonOperator) -> Series:
         return self._from_pyseries(f(other))
 
     @overload  # type: ignore[override]
-    def __eq__(self, other: Expr) -> Expr: ...
+    def __eq__(self, other: Expr) -> Expr: ...  # type: ignore[overload-overlap]
 
     @overload
-    def __eq__(self, other: Any) -> Series: ...
+    def __eq__(self, other: object) -> Series: ...
 
-    def __eq__(self, other: Any) -> Series | Expr:
+    def __eq__(self, other: object) -> Series | Expr:
         warn_null_comparison(other)
         if isinstance(other, pl.Expr):
             return F.lit(self).__eq__(other)
         return self._comp(other, "eq")
 
     @overload  # type: ignore[override]
-    def __ne__(self, other: Expr) -> Expr: ...
+    def __ne__(self, other: Expr) -> Expr: ...  # type: ignore[overload-overlap]
 
     @overload
-    def __ne__(self, other: Any) -> Series: ...
+    def __ne__(self, other: object) -> Series: ...
 
-    def __ne__(self, other: Any) -> Series | Expr:
+    def __ne__(self, other: object) -> Series | Expr:
         warn_null_comparison(other)
         if isinstance(other, pl.Expr):
             return F.lit(self).__ne__(other)
@@ -3974,7 +3974,7 @@ def equals(
 
     def cast(
         self,
-        dtype: PolarsDataType | type[int] | type[float] | type[str] | type[bool],
+        dtype: type[int | float | str | bool] | PolarsDataType,
         *,
         strict: bool = True,
         wrap_numerical: bool = False,
diff --git a/py-polars/polars/series/string.py b/py-polars/polars/series/string.py
index 953803fc1253..e2104f67af44 100644
--- a/py-polars/polars/series/string.py
+++ b/py-polars/polars/series/string.py
@@ -29,7 +29,7 @@ class StringNameSpace:
 
     _accessor = "str"
 
-    def __init__(self, series: Series):
+    def __init__(self, series: Series) -> None:
         self._s: PySeries = series._s
 
     def to_date(
diff --git a/py-polars/polars/series/struct.py b/py-polars/polars/series/struct.py
index 160558a207b8..750ccfd51275 100644
--- a/py-polars/polars/series/struct.py
+++ b/py-polars/polars/series/struct.py
@@ -20,7 +20,7 @@ class StructNameSpace:
 
     _accessor = "struct"
 
-    def __init__(self, series: Series):
+    def __init__(self, series: Series) -> None:
         self._s: PySeries = series._s
 
     def __getitem__(self, item: int | str) -> Series:
diff --git a/py-polars/polars/string_cache.py b/py-polars/polars/string_cache.py
index f2bacc72b39b..e4768de6217d 100644
--- a/py-polars/polars/string_cache.py
+++ b/py-polars/polars/string_cache.py
@@ -8,8 +8,15 @@
     from polars.polars import PyStringCacheHolder
 
 if TYPE_CHECKING:
+    import sys
     from types import TracebackType
 
+    if sys.version_info >= (3, 11):
+        from typing import Self
+    else:
+        from typing_extensions import Self
+
+
 __all__ = [
     "StringCache",
     "disable_string_cache",
@@ -68,7 +75,7 @@ class StringCache(contextlib.ContextDecorator):
     ...     return pl.concat([s1, s2])
     """
 
-    def __enter__(self) -> StringCache:
+    def __enter__(self) -> Self:
         self._string_cache = PyStringCacheHolder()
         return self
 
diff --git a/py-polars/polars/testing/parametric/strategies/core.py b/py-polars/polars/testing/parametric/strategies/core.py
index 659a6f2433b7..b3aef2e51301 100644
--- a/py-polars/polars/testing/parametric/strategies/core.py
+++ b/py-polars/polars/testing/parametric/strategies/core.py
@@ -29,7 +29,7 @@
 
 
 @st.composite
-def series(  # noqa: D417
+def series(
     draw: DrawFn,
     /,
     *,
@@ -267,7 +267,7 @@ def dataframes(
 
 
 @st.composite
-def dataframes(  # noqa: D417
+def dataframes(
     draw: DrawFn,
     /,
     cols: int | column | Sequence[column] | None = None,
diff --git a/py-polars/pyproject.toml b/py-polars/pyproject.toml
index efa5bd1f15f9..86e5660dc8a3 100644
--- a/py-polars/pyproject.toml
+++ b/py-polars/pyproject.toml
@@ -151,59 +151,60 @@ fix = true
 
 [tool.ruff.lint]
 select = [
-  "E", # pycodestyle
-  "W", # pycodestyle
-  "F", # Pyflakes
+  "ANN", # flake8-annotations
   "B", # flake8-bugbear
   "C4", # flake8-comprehensions
   "D", # flake8-docstrings
-  "D213", # Augment NumPy docstring convention: Multi-line docstring summary should start at the second line
-  "D417", # Augment NumPy docstring convention: Missing argument descriptions
+  "E", # pycodestyle
+  "EM", # flake8-errmsg
+  "F", # pyflakes
+  "FA", # flake8-future-annotations
+  "FBT001", # flake8-boolean-trap
   "I", # isort
-  "SIM", # flake8-simplify
-  "TCH", # flake8-type-checking
-  "TID", # flake8-tidy-imports
-  "UP", # pyupgrade
+  "ICN", # flake8-import-conventions
+  "INT", # flake8-gettext
+  "PERF", # perflint
+  "PIE", # flake8-pie
   "PT", # flake8-pytest-style
-  "RUF", # Ruff-specific rules
   "PTH", # flake8-use-pathlib
-  "FA", # flake8-future-annotations
-  "PIE", # flake8-pie
+  "PYI", # flake8-pyi
+  "RUF", # ruff-specific rules
+  "SIM", # flake8-simplify
+  "TCH", # flake8-type-checking
   "TD", # flake8-todos
+  "TID", # flake8-tidy-imports
   "TRY", # tryceratops
-  "EM", # flake8-errmsg
-  "FBT001", # flake8-boolean-trap
+  "UP", # pyupgrade
+  "W", # pycodestyle
 ]
 
 ignore = [
-  # Line length regulated by formatter
-  "E501",
-  # pydocstyle: http://www.pydocstyle.org/en/stable/error_codes.html
-  "D401", # Relax NumPy docstring convention: First line should be in imperative mood
-  # flake8-pytest-style:
-  "PT011", # pytest.raises({exception}) is too broad, set the match parameter or use a more specific exception
-  # flake8-simplify
-  "SIM102", # Use a single `if` statement instead of nested `if` statements
-  "SIM108", # Use ternary operator
-  # ruff
-  "RUF005", # unpack-instead-of-concatenating-to-collection-literal
-  # pycodestyle
+  # ------------------------------------------------------------------
   # TODO: Remove errors below to further improve docstring linting
-  # Ordered from most common to least common errors.
-  "D105", # Missing docstring in magic method
+  # ------------------------------------------------------------------
   "D100", # Missing docstring in public module
   "D104", # Missing docstring in public package
-  # flake8-todos
+  "D105", # Missing docstring in magic method
+  # ------------------------------------------------------------------
+  "ANN101", # Missing type annotation for `self` in method
+  "ANN102", # Missing type annotation for `cls` in classmethod
+  "ANN401", # Dynamically typed expressions (Any) are disallowed
+  "D401", # Relax NumPy docstring convention: first line should be imperative
+  "E501", # Line length regulated by formatter
+  "PT011", # pytest.raises is too broad, set match or use a more specific exception
+  "PYI041", # Use float instead of int | float
+  "RUF022", # `__all__` is not sorted
+  "RUF005", # Consider expression instead of concatenation
+  "SIM102", # Use a single `if` statement instead of nested `if` statements
+  "SIM108", # Use ternary operator
   "TD002", # Missing author in TODO
   "TD003", # Missing issue link on the line following this TODO
-  # tryceratops
   "TRY003", # Avoid specifying long messages outside the exception class
-  # Lints below are turned off because of conflicts with the ruff formatter
-  "D206",
-  "W191",
 ]
+allowed-confusables = ["µ"]
 
 [tool.ruff.lint.per-file-ignores]
+"dependencies.py" = ["ICN001"]
 "tests/**/*.py" = ["D100", "D102", "D103", "B018", "FBT001"]
 
 [tool.ruff.lint.pycodestyle]
diff --git a/py-polars/requirements-lint.txt b/py-polars/requirements-lint.txt
index 28c5e645e0d3..1490335f9266 100644
--- a/py-polars/requirements-lint.txt
+++ b/py-polars/requirements-lint.txt
@@ -1,3 +1,3 @@
 mypy==1.11.1
-ruff==0.6.3
+ruff==0.6.4
 typos==1.24.2
diff --git a/py-polars/tests/benchmark/data/__init__.py b/py-polars/tests/benchmark/data/__init__.py
index 255752458b72..84b7ef3683ce 100644
--- a/py-polars/tests/benchmark/data/__init__.py
+++ b/py-polars/tests/benchmark/data/__init__.py
@@ -3,4 +3,7 @@
 from tests.benchmark.data.h2oai import generate_group_by_data
 from tests.benchmark.data.pdsh import load_pdsh_table
 
-__all__ = ["load_pdsh_table", "generate_group_by_data"]
+__all__ = [
+    "generate_group_by_data",
+    "load_pdsh_table",
+]
diff --git a/py-polars/tests/docs/run_doctest.py b/py-polars/tests/docs/run_doctest.py
index 09ad6b41c14d..353b9cfb0dd0 100644
--- a/py-polars/tests/docs/run_doctest.py
+++ b/py-polars/tests/docs/run_doctest.py
@@ -39,7 +39,7 @@
 from tempfile import TemporaryDirectory
 from typing import TYPE_CHECKING, Any, Iterator
 
-import polars
+import polars as pl
 
 if TYPE_CHECKING:
     from types import ModuleType
@@ -67,15 +67,15 @@
 for mod, methods in OPTIONAL_MODULES_AND_METHODS.items():
     try:
         importlib.import_module(mod)
-    except ImportError:
+    except ImportError:  # noqa: PERF203
         SKIP_METHODS.update(methods)
         OPTIONAL_MODULES.add(mod)
 
 
 def doctest_teardown(d: doctest.DocTest) -> None:
     # don't let config changes or string cache state leak between tests
-    polars.Config.restore_defaults()
-    polars.disable_string_cache()
+    pl.Config.restore_defaults()
+    pl.disable_string_cache()
 
 
 def modules_in_path(p: Path) -> Iterator[ModuleType]:
@@ -86,7 +86,7 @@ def modules_in_path(p: Path) -> Iterator[ModuleType]:
             file_name_import = ".".join(file.relative_to(p).parts)[:-3]
             temp_module = importlib.import_module(p.name + "." + file_name_import)
             yield temp_module
-        except ImportError as err:
+        except ImportError as err:  # noqa: PERF203
             if not any(re.search(rf"\b{mod}\b", str(err)) for mod in OPTIONAL_MODULES):
                 raise
 
@@ -152,14 +152,14 @@ def check_output(self, want: str, got: str, optionflags: Any) -> bool:
     # doctest.REPORT_NDIFF = True
 
     # __file__ returns the __init__.py, so grab the parent
-    src_dir = Path(polars.__file__).parent
+    src_dir = Path(pl.__file__).parent
 
     with TemporaryDirectory() as tmpdir:
         # collect all tests
         tests = [
             doctest.DocTestSuite(
                 m,
-                extraglobs={"pl": polars, "dirpath": Path(tmpdir)},
+                extraglobs={"pl": pl, "dirpath": Path(tmpdir)},
                 tearDown=doctest_teardown,
                 optionflags=1,
             )
@@ -168,7 +168,7 @@ def check_output(self, want: str, got: str, optionflags: Any) -> bool:
         test_suite = FilteredTestSuite(tests)
 
         # Ensure that we clean up any artifacts produced by the doctests
-        # with patch(polars.DataFrame.write_csv):
+        # with patch(pl.DataFrame.write_csv):
         # run doctests and report
         result = unittest.TextTestRunner().run(test_suite)
         success_flag = (result.testsRun > 0) & (len(result.failures) == 0)
diff --git a/py-polars/tests/docs/test_user_guide.py b/py-polars/tests/docs/test_user_guide.py
index 89203b4d09eb..df3fd52494f8 100644
--- a/py-polars/tests/docs/test_user_guide.py
+++ b/py-polars/tests/docs/test_user_guide.py
@@ -5,11 +5,11 @@
 from pathlib import Path
 from typing import Iterator
 
-import matplotlib
+import matplotlib as mpl
 import pytest
 
 # Do not show plots
-matplotlib.use("Agg")
+mpl.use("Agg")
 
 # Get paths to Python code snippets
 repo_root = Path(__file__).parent.parent.parent.parent
diff --git a/py-polars/tests/unit/constructors/test_constructors.py b/py-polars/tests/unit/constructors/test_constructors.py
index fda072930525..dbfe77b46c97 100644
--- a/py-polars/tests/unit/constructors/test_constructors.py
+++ b/py-polars/tests/unit/constructors/test_constructors.py
@@ -458,9 +458,15 @@ class ABC:
     assert dataclasses.asdict(abc) == df.rows(named=True)[0]
 
 
-def test_collections_namedtuple() -> None:
-    TestData = namedtuple("TestData", ["id", "info"])
-    nt_data = [TestData(1, "a"), TestData(2, "b"), TestData(3, "c")]
+@pytest.mark.parametrize(
+    "nt",
+    [
+        namedtuple("TestData", ["id", "info"]),  # noqa: PYI024
+        NamedTuple("TestData", [("id", int), ("info", str)]),
+    ],
+)
+def test_collections_namedtuple(nt: type) -> None:
+    nt_data = [nt(1, "a"), nt(2, "b"), nt(3, "c")]
 
     result = pl.DataFrame(nt_data)
     expected = pl.DataFrame({"id": [1, 2, 3], "info": ["a", "b", "c"]})
diff --git a/py-polars/tests/unit/constructors/test_dataframe.py b/py-polars/tests/unit/constructors/test_dataframe.py
index b193c99f5011..3703475aa438 100644
--- a/py-polars/tests/unit/constructors/test_dataframe.py
+++ b/py-polars/tests/unit/constructors/test_dataframe.py
@@ -37,9 +37,9 @@ class Foo:
         def __init__(self, value: int) -> None:
             self._value = value
 
-        def __eq__(self, other: Any) -> bool:
+        def __eq__(self, other: object) -> bool:
             return issubclass(other.__class__, self.__class__) and (
-                self._value == other._value
+                self._value == other._value  # type: ignore[attr-defined]
             )
 
         def __repr__(self) -> str:
diff --git a/py-polars/tests/unit/dataframe/test_df.py b/py-polars/tests/unit/dataframe/test_df.py
index ab27d2647395..71b012945876 100644
--- a/py-polars/tests/unit/dataframe/test_df.py
+++ b/py-polars/tests/unit/dataframe/test_df.py
@@ -1189,7 +1189,7 @@ def gen(n: int, *, strkey: bool = True) -> Iterator[Any]:
 
     # iterable object
     class Rows:
-        def __init__(self, n: int, *, strkey: bool = True):
+        def __init__(self, n: int, *, strkey: bool = True) -> None:
             self._n = n
             self._strkey = strkey
 
@@ -1586,7 +1586,7 @@ class Foo:
         def __hash__(self) -> int:
             return 0
 
-        def __eq__(self, other: Any) -> bool:
+        def __eq__(self, other: object) -> bool:
             return True
 
     df = df.with_columns(pl.col("a").map_elements(lambda x: Foo()).alias("foo"))
@@ -2514,7 +2514,7 @@ def test_set() -> None:
 
     # needs to be a 2 element tuple
     with pytest.raises(ValueError):
-        df[(1, 2, 3)] = 1
+        df[1, 2, 3] = 1
 
     # we cannot index with any type, such as bool
     with pytest.raises(TypeError):
diff --git a/py-polars/tests/unit/dataframe/test_partition_by.py b/py-polars/tests/unit/dataframe/test_partition_by.py
index c78a7043d4b7..5a0f145d7805 100644
--- a/py-polars/tests/unit/dataframe/test_partition_by.py
+++ b/py-polars/tests/unit/dataframe/test_partition_by.py
@@ -53,11 +53,11 @@ def test_partition_by_single(df: pl.DataFrame) -> None:
 def test_partition_by_as_dict() -> None:
     df = pl.DataFrame({"a": ["one", "two", "one", "two"], "b": [1, 2, 3, 4]})
     result = df.partition_by(cs.all(), as_dict=True)
-    result_first = result[("one", 1)]
+    result_first = result["one", 1]
     assert result_first.to_dict(as_series=False) == {"a": ["one"], "b": [1]}
 
     result = df.partition_by("a", as_dict=True)
-    result_first = result[("one",)]
+    result_first = result["one",]
     assert result_first.to_dict(as_series=False) == {"a": ["one", "one"], "b": [1, 3]}
 
 
@@ -65,7 +65,7 @@ def test_partition_by_as_dict_include_keys_false() -> None:
     df = pl.DataFrame({"a": ["one", "two", "one", "two"], "b": [1, 2, 3, 4]})
 
     result = df.partition_by("a", include_key=False, as_dict=True)
-    result_first = result[("one",)]
+    result_first = result["one",]
     assert result_first.to_dict(as_series=False) == {"b": [1, 3]}
 
 
diff --git a/py-polars/tests/unit/datatypes/test_object.py b/py-polars/tests/unit/datatypes/test_object.py
index 8db373d3f58a..955461eac959 100644
--- a/py-polars/tests/unit/datatypes/test_object.py
+++ b/py-polars/tests/unit/datatypes/test_object.py
@@ -166,7 +166,7 @@ def test_null_obj_str_13512() -> None:
 
 def test_format_object_series_14267() -> None:
     s = pl.Series([Path(), Path("abc")])
-    expected = "shape: (2,)\n" "Series: '' [o][object]\n" "[\n" "\t.\n" "\tabc\n" "]"
+    expected = "shape: (2,)\nSeries: '' [o][object]\n[\n\t.\n\tabc\n]"
     assert str(s) == expected
 
 
diff --git a/py-polars/tests/unit/interop/numpy/test_ufunc_expr.py b/py-polars/tests/unit/interop/numpy/test_ufunc_expr.py
index bba5c72b6fc7..1fe9ea3ed4be 100644
--- a/py-polars/tests/unit/interop/numpy/test_ufunc_expr.py
+++ b/py-polars/tests/unit/interop/numpy/test_ufunc_expr.py
@@ -137,7 +137,7 @@ def test_generalized_ufunc_scalar() -> None:
     numba = pytest.importorskip("numba")
 
     @numba.guvectorize([(numba.int64[:], numba.int64[:])], "(n)->()")  # type: ignore[misc]
-    def my_custom_sum(arr, result) -> None:  # type: ignore[no-untyped-def]
+    def my_custom_sum(arr, result) -> None:  # type: ignore[no-untyped-def]  # noqa: ANN001
         total = 0
         for value in arr:
             total += value
diff --git a/py-polars/tests/unit/interop/test_interop.py b/py-polars/tests/unit/interop/test_interop.py
index 1730a5c6f8bb..7f664e2fb197 100644
--- a/py-polars/tests/unit/interop/test_interop.py
+++ b/py-polars/tests/unit/interop/test_interop.py
@@ -5,7 +5,6 @@
 
 import numpy as np
 import pandas as pd
-import pyarrow
 import pyarrow as pa
 import pytest
 
@@ -721,27 +720,27 @@ def test_compat_level(monkeypatch: pytest.MonkeyPatch) -> None:
     str_col = pl.Series(["awd"])
     bin_col = pl.Series([b"dwa"])
     assert str_col._newest_compat_level() == newest._version  # type: ignore[attr-defined]
-    assert isinstance(str_col.to_arrow(), pyarrow.LargeStringArray)
-    assert isinstance(str_col.to_arrow(compat_level=oldest), pyarrow.LargeStringArray)
-    assert isinstance(str_col.to_arrow(compat_level=newest), pyarrow.StringViewArray)
-    assert isinstance(bin_col.to_arrow(), pyarrow.LargeBinaryArray)
-    assert isinstance(bin_col.to_arrow(compat_level=oldest), pyarrow.LargeBinaryArray)
-    assert isinstance(bin_col.to_arrow(compat_level=newest), pyarrow.BinaryViewArray)
+    assert isinstance(str_col.to_arrow(), pa.LargeStringArray)
+    assert isinstance(str_col.to_arrow(compat_level=oldest), pa.LargeStringArray)
+    assert isinstance(str_col.to_arrow(compat_level=newest), pa.StringViewArray)
+    assert isinstance(bin_col.to_arrow(), pa.LargeBinaryArray)
+    assert isinstance(bin_col.to_arrow(compat_level=oldest), pa.LargeBinaryArray)
+    assert isinstance(bin_col.to_arrow(compat_level=newest), pa.BinaryViewArray)
 
     df = pl.DataFrame({"str_col": str_col, "bin_col": bin_col})
-    assert isinstance(df.to_arrow()["str_col"][0], pyarrow.LargeStringScalar)
+    assert isinstance(df.to_arrow()["str_col"][0], pa.LargeStringScalar)
     assert isinstance(
-        df.to_arrow(compat_level=oldest)["str_col"][0], pyarrow.LargeStringScalar
+        df.to_arrow(compat_level=oldest)["str_col"][0], pa.LargeStringScalar
     )
     assert isinstance(
-        df.to_arrow(compat_level=newest)["str_col"][0], pyarrow.StringViewScalar
+        df.to_arrow(compat_level=newest)["str_col"][0], pa.StringViewScalar
     )
-    assert isinstance(df.to_arrow()["bin_col"][0], pyarrow.LargeBinaryScalar)
+    assert isinstance(df.to_arrow()["bin_col"][0], pa.LargeBinaryScalar)
     assert isinstance(
-        df.to_arrow(compat_level=oldest)["bin_col"][0], pyarrow.LargeBinaryScalar
+        df.to_arrow(compat_level=oldest)["bin_col"][0], pa.LargeBinaryScalar
     )
     assert isinstance(
-        df.to_arrow(compat_level=newest)["bin_col"][0], pyarrow.BinaryViewScalar
+        df.to_arrow(compat_level=newest)["bin_col"][0], pa.BinaryViewScalar
     )
 
     assert len(df.write_ipc(None).getbuffer()) == 786
diff --git a/py-polars/tests/unit/io/database/test_async.py b/py-polars/tests/unit/io/database/test_async.py
index b51a01c8e37e..a8492e7a5276 100644
--- a/py-polars/tests/unit/io/database/test_async.py
+++ b/py-polars/tests/unit/io/database/test_async.py
@@ -50,7 +50,7 @@ async def __aenter__(self) -> Any:
         await self.connect()
         return self
 
-    async def __aexit__(self, *args: Any, **kwargs: Any) -> None:
+    async def __aexit__(self, *args: object, **kwargs: Any) -> None:
         await self.close()
 
     async def close(self) -> None:
diff --git a/py-polars/tests/unit/io/database/test_read.py b/py-polars/tests/unit/io/database/test_read.py
index b50e88602dac..967379f356f7 100644
--- a/py-polars/tests/unit/io/database/test_read.py
+++ b/py-polars/tests/unit/io/database/test_read.py
@@ -108,7 +108,7 @@ def __init__(
         batched: bool,
         exact_batch_size: bool,
         repeat_batch_calls: bool = False,
-    ):
+    ) -> None:
         self.test_data = test_data
         self.repeat_batched_calls = repeat_batch_calls
         self.exact_batch_size = exact_batch_size
diff --git a/py-polars/tests/unit/io/test_csv.py b/py-polars/tests/unit/io/test_csv.py
index fcacedead1d4..dff14d620d4a 100644
--- a/py-polars/tests/unit/io/test_csv.py
+++ b/py-polars/tests/unit/io/test_csv.py
@@ -760,9 +760,9 @@ def test_ignore_try_parse_dates() -> None:
     ).encode()
 
     headers = ["a", "b", "c"]
-    dtypes: dict[str, type[pl.DataType]] = {
-        k: pl.String for k in headers
-    }  # Forces String type for every column
+    dtypes: dict[str, type[pl.DataType]] = dict.fromkeys(
+        headers, pl.String
+    )  # Forces String type for every column
     df = pl.read_csv(csv, columns=headers, schema_overrides=dtypes)
     assert df.dtypes == [pl.String, pl.String, pl.String]
 
@@ -1449,7 +1449,7 @@ def test_duplicated_columns() -> None:
 
 
 def test_error_message() -> None:
-    data = io.StringIO("target,wind,energy,miso\n" "1,2,3,4\n" "1,2,1e5,1\n")
+    data = io.StringIO("target,wind,energy,miso\n1,2,3,4\n1,2,1e5,1\n")
     with pytest.raises(
         ComputeError,
         match=r"could not parse `1e5` as dtype `i64` at column 'energy' \(column number 3\)",
@@ -1717,10 +1717,8 @@ def test_csv_multiline_splits() -> None:
     def some_multiline_str(n: int) -> str:
         strs = []
         strs.append('"')
-        # sample between 0 and 5 so that it is likely
-        # the multiline field also go 3 separators.
-        for length in np.random.randint(0, 5, n):
-            strs.append(f"{'xx,' * length}")
+        # sample between 0-5 so it is likely the multiline field also gets 3 separators.
+        strs.extend(f"{'xx,' * length}" for length in np.random.randint(0, 5, n))
 
         strs.append('"')
         return "\n".join(strs)
@@ -1993,7 +1991,7 @@ def test_empty_csv_no_raise() -> None:
 
 
 def test_csv_no_new_line_last() -> None:
-    csv = io.StringIO("a b\n" "1 1\n" "2 2\n" "3 2.1")
+    csv = io.StringIO("a b\n1 1\n2 2\n3 2.1")
     assert pl.read_csv(csv, separator=" ").to_dict(as_series=False) == {
         "a": [1, 2, 3],
         "b": [1.0, 2.0, 2.1],
diff --git a/py-polars/tests/unit/io/test_lazy_count_star.py b/py-polars/tests/unit/io/test_lazy_count_star.py
index a2c03596dd15..6a57dee9487d 100644
--- a/py-polars/tests/unit/io/test_lazy_count_star.py
+++ b/py-polars/tests/unit/io/test_lazy_count_star.py
@@ -30,18 +30,12 @@ def test_count_csv(io_files_path: Path, path: str, n_rows: int) -> None:
 @pytest.mark.write_disk
 def test_commented_csv() -> None:
     csv_a = NamedTemporaryFile()
-    csv_a.write(
-        b"""
-A,B
-Gr1,A
-Gr1,B
-# comment line
-    """.strip()
-    )
+    csv_a.write(b"A,B\nGr1,A\nGr1,B\n# comment line\n")
     csv_a.seek(0)
 
     expected = pl.DataFrame(pl.Series("len", [2], dtype=pl.UInt32))
     lf = pl.scan_csv(csv_a.name, comment_prefix="#").select(pl.len())
+
     assert "FAST COUNT" in lf.explain()
     assert_frame_equal(lf.collect(), expected)
 
diff --git a/py-polars/tests/unit/io/test_parquet.py b/py-polars/tests/unit/io/test_parquet.py
index e035a44686f0..10aa23dfa7b6 100644
--- a/py-polars/tests/unit/io/test_parquet.py
+++ b/py-polars/tests/unit/io/test_parquet.py
@@ -1731,7 +1731,7 @@ def test_different_page_validity_across_pages(value: str | int | float | bool) -
 def test_delta_length_byte_array_prefiltering(df: pl.DataFrame) -> None:
     cols = df.columns
 
-    encodings = {col: "DELTA_LENGTH_BYTE_ARRAY" for col in cols}
+    encodings = dict.fromkeys(cols, "DELTA_LENGTH_BYTE_ARRAY")
     encodings["filter_col"] = "PLAIN"
 
     f = io.BytesIO()
diff --git a/py-polars/tests/unit/io/test_scan.py b/py-polars/tests/unit/io/test_scan.py
index d710954fcbfe..8fdfb83f44ec 100644
--- a/py-polars/tests/unit/io/test_scan.py
+++ b/py-polars/tests/unit/io/test_scan.py
@@ -48,10 +48,10 @@ def _scan(
 
     if (
         scan_func := {
-            ".ipc"     : pl.scan_ipc,
-            ".parquet" : pl.scan_parquet,
-            ".csv"     : pl.scan_csv,
-            ".ndjson"  : pl.scan_ndjson,
+            ".ipc": pl.scan_ipc,
+            ".parquet": pl.scan_parquet,
+            ".csv": pl.scan_csv,
+            ".ndjson": pl.scan_ndjson,
         }.get(suffix)
     ) is not None:  # fmt: skip
         result = scan_func(
@@ -72,10 +72,10 @@ def _write(df: pl.DataFrame, file_path: Path) -> None:
 
     if (
         write_func := {
-            ".ipc"     : pl.DataFrame.write_ipc,
-            ".parquet" : pl.DataFrame.write_parquet,
-            ".csv"     : pl.DataFrame.write_csv,
-            ".ndjson"  : pl.DataFrame.write_ndjson,
+            ".ipc": pl.DataFrame.write_ipc,
+            ".parquet": pl.DataFrame.write_parquet,
+            ".csv": pl.DataFrame.write_csv,
+            ".ndjson": pl.DataFrame.write_ndjson,
         }.get(suffix)
     ) is not None:  # fmt: skip
         return write_func(df, file_path)  # type: ignore[operator, no-any-return]
diff --git a/py-polars/tests/unit/operations/map/test_inefficient_map_warning.py b/py-polars/tests/unit/operations/map/test_inefficient_map_warning.py
index 57a8ce795dc1..74946f084d51 100644
--- a/py-polars/tests/unit/operations/map/test_inefficient_map_warning.py
+++ b/py-polars/tests/unit/operations/map/test_inefficient_map_warning.py
@@ -9,8 +9,7 @@
 from math import cosh
 from typing import Any, Callable
 
-import numpy
-import numpy as np  # noqa: F401
+import numpy as np
 import pytest
 
 import polars as pl
@@ -103,7 +102,7 @@
     ("e", "lambda x: np.arcsinh(x)", 'pl.col("e").arcsinh()'),
     ("e", "lambda x: np.arctan(x)", 'pl.col("e").arctan()'),
     ("e", "lambda x: np.arctanh(x)", 'pl.col("e").arctanh()'),
-    ("a", "lambda x: 0 + numpy.cbrt(x)", '0 + pl.col("a").cbrt()'),
+    ("a", "lambda x: 0 + np.cbrt(x)", '0 + pl.col("a").cbrt()'),
     ("e", "lambda x: np.ceil(x)", 'pl.col("e").ceil()'),
     ("e", "lambda x: np.cos(x)", 'pl.col("e").cos()'),
     ("e", "lambda x: np.cosh(x)", 'pl.col("e").cosh()'),
@@ -259,7 +258,7 @@
     "datetime": datetime,
     "dt": dt,
     "math": math,
-    "np": numpy,
+    "np": np,
     "pl": pl,
 }
 
@@ -330,7 +329,7 @@ def test_parse_apply_raw_functions() -> None:
 
     # test bare 'numpy' functions
     for func_name in _NUMPY_FUNCTIONS:
-        func = getattr(numpy, func_name)
+        func = getattr(np, func_name)
 
         # note: we can't parse/rewrite raw numpy functions...
         parser = BytecodeParser(func, map_target="expr")
@@ -355,7 +354,7 @@ def test_parse_apply_raw_functions() -> None:
             pl.col("value").str.json_decode(),
             pl.col("value").map_elements(json.loads),
         ):
-            result_frames.append(
+            result_frames.append(  # noqa: PERF401
                 pl.LazyFrame({"value": ['{"a":1, "b": true, "c": "xx"}', None]})
                 .select(extracted=expr)
                 .unnest("extracted")
@@ -411,10 +410,8 @@ def mcosh(self, x: float) -> float:
     ):
         s = pl.Series("srs", [0, 1, 2, 3, 4])
         assert_series_equal(
-            s.map_elements(
-                lambda x: numpy.cos(3) + x - abs(-1), return_dtype=pl.Float64
-            ),
-            numpy.cos(3) + s - 1,
+            s.map_elements(lambda x: np.cos(3) + x - abs(-1), return_dtype=pl.Float64),
+            np.cos(3) + s - 1,
         )
 
     # if 's' is already the name of a global variable then the series alias
diff --git a/py-polars/tests/unit/operations/map/test_map_groups.py b/py-polars/tests/unit/operations/map/test_map_groups.py
index e8f5554333b1..d675d43e28f6 100644
--- a/py-polars/tests/unit/operations/map/test_map_groups.py
+++ b/py-polars/tests/unit/operations/map/test_map_groups.py
@@ -119,7 +119,7 @@ def test_map_groups_object_output() -> None:
     )
 
     class Foo:
-        def __init__(self, payload: Any):
+        def __init__(self, payload: Any) -> None:
             self.payload = payload
 
     result = df.group_by("groups").agg(
diff --git a/py-polars/tests/unit/operations/namespaces/temporal/test_to_datetime.py b/py-polars/tests/unit/operations/namespaces/temporal/test_to_datetime.py
index 08ab045467ca..5bb09a0f8d1c 100644
--- a/py-polars/tests/unit/operations/namespaces/temporal/test_to_datetime.py
+++ b/py-polars/tests/unit/operations/namespaces/temporal/test_to_datetime.py
@@ -55,7 +55,7 @@
     for fraction in FRACTIONS
     if time_format.endswith("%S") or fraction == ""
     for tz in TIMEZONES
-    if date_format.startswith("%Y") and time_format != "" or tz == ""
+    if (date_format.startswith("%Y") and time_format != "") or tz == ""
 ]
 
 
diff --git a/py-polars/tests/unit/operations/namespaces/test_binary.py b/py-polars/tests/unit/operations/namespaces/test_binary.py
index 92432dd74592..e15ca2010817 100644
--- a/py-polars/tests/unit/operations/namespaces/test_binary.py
+++ b/py-polars/tests/unit/operations/namespaces/test_binary.py
@@ -50,7 +50,7 @@ def test_contains() -> None:
             expected == df.select(pl.col("bin").bin.contains(pattern))["bin"].to_list()
         )
         # frame filter
-        assert sum([e for e in expected if e is True]) == len(
+        assert sum(e for e in expected if e is True) == len(
             df.filter(pl.col("bin").bin.contains(pattern))
         )
 
diff --git a/py-polars/tests/unit/operations/test_cast.py b/py-polars/tests/unit/operations/test_cast.py
index 1b00c4fb0fe3..cdf7688f7c32 100644
--- a/py-polars/tests/unit/operations/test_cast.py
+++ b/py-polars/tests/unit/operations/test_cast.py
@@ -313,7 +313,6 @@ def _cast_lit_t(
         "expected_value",
     ),
     [
-        # fmt: off
         # date to datetime
         (date(1970, 1, 1), pl.Date, pl.Datetime("ms"), True, datetime(1970, 1, 1)),
         (date(1970, 1, 1), pl.Date, pl.Datetime("us"), True, datetime(1970, 1, 1)),
@@ -350,7 +349,6 @@ def _cast_lit_t(
         (date(2149, 6, 7), pl.Date, pl.Int16, False, None),
         (datetime(9999, 12, 31), pl.Datetime, pl.Int8, False, None),
         (datetime(9999, 12, 31), pl.Datetime, pl.Int16, False, None),
-        # fmt: on
     ],
 )
 def test_strict_cast_temporal(
@@ -388,7 +386,6 @@ def test_strict_cast_temporal(
         "expected_value",
     ),
     [
-        # fmt: off
         # date to datetime
         (date(1970, 1, 1), pl.Date, pl.Datetime("ms"), datetime(1970, 1, 1)),
         (date(1970, 1, 1), pl.Date, pl.Datetime("us"), datetime(1970, 1, 1)),
@@ -425,7 +422,6 @@ def test_strict_cast_temporal(
         (date(2149, 6, 7), pl.Date, pl.Int16, None),
         (datetime(9999, 12, 31), pl.Datetime, pl.Int8, None),
         (datetime(9999, 12, 31), pl.Datetime, pl.Int16, None),
-        # fmt: on
     ],
 )
 def test_cast_temporal(
diff --git a/py-polars/tests/unit/operations/test_comparison.py b/py-polars/tests/unit/operations/test_comparison.py
index 42535cff85a6..72771ff64eab 100644
--- a/py-polars/tests/unit/operations/test_comparison.py
+++ b/py-polars/tests/unit/operations/test_comparison.py
@@ -236,7 +236,7 @@ def verify_total_ordering(
         "ne_missing": [refmiss != "="],
     }
     ans_correct = pl.DataFrame(
-        ans_correct_dict, schema={c: pl.Boolean for c in ans_correct_dict}
+        ans_correct_dict, schema=dict.fromkeys(ans_correct_dict, pl.Boolean)
     )
 
     assert_frame_equal(ans[:1], ans_correct)
@@ -287,7 +287,7 @@ def verify_total_ordering_broadcast(
         "ne_missing": [refmiss != "="],
     }
     ans_correct = pl.DataFrame(
-        ans_correct_dict, schema={c: pl.Boolean for c in ans_correct_dict}
+        ans_correct_dict, schema=dict.fromkeys(ans_correct_dict, pl.Boolean)
     )
 
     assert_frame_equal(ans_first[:1], ans_correct)
diff --git a/py-polars/tests/unit/operations/test_group_by.py b/py-polars/tests/unit/operations/test_group_by.py
index 09864b329c22..af9dc9a180e2 100644
--- a/py-polars/tests/unit/operations/test_group_by.py
+++ b/py-polars/tests/unit/operations/test_group_by.py
@@ -371,7 +371,7 @@ def test_group_by_iteration() -> None:
 def test_group_by_iteration_selector() -> None:
     df = pl.DataFrame({"a": ["one", "two", "one", "two"], "b": [1, 2, 3, 4]})
     result = dict(df.group_by(cs.string()))
-    result_first = result[("one",)]
+    result_first = result["one",]
     assert result_first.to_dict(as_series=False) == {"a": ["one", "one"], "b": [1, 3]}
 
 
diff --git a/py-polars/tests/unit/series/test_series.py b/py-polars/tests/unit/series/test_series.py
index 3f7f159ccae0..2a4d6f1d5285 100644
--- a/py-polars/tests/unit/series/test_series.py
+++ b/py-polars/tests/unit/series/test_series.py
@@ -9,7 +9,6 @@
 import pyarrow as pa
 import pytest
 
-import polars
 import polars as pl
 from polars._utils.construction import iterable_to_pyseries
 from polars.datatypes import (
@@ -959,7 +958,7 @@ def test_round_sig_figs(
 
 
 def test_round_sig_figs_raises_exc() -> None:
-    with pytest.raises(polars.exceptions.InvalidOperationError):
+    with pytest.raises(pl.exceptions.InvalidOperationError):
         pl.Series([1.234, 0.1234]).round_sig_figs(digits=0)
 
 
@@ -1153,7 +1152,7 @@ def gen(n: int) -> Iterator[int]:
 
     # iterable object
     class Data:
-        def __init__(self, n: int):
+        def __init__(self, n: int) -> None:
             self._n = n
 
         def __iter__(self) -> Iterator[int]:
diff --git a/py-polars/tests/unit/test_api.py b/py-polars/tests/unit/test_api.py
index a90bc5ceb68d..c49254801562 100644
--- a/py-polars/tests/unit/test_api.py
+++ b/py-polars/tests/unit/test_api.py
@@ -11,7 +11,7 @@
 def test_custom_df_namespace() -> None:
     @pl.api.register_dataframe_namespace("split")
     class SplitFrame:
-        def __init__(self, df: pl.DataFrame):
+        def __init__(self, df: pl.DataFrame) -> None:
             self._df = df
 
         def by_first_letter_of_column_names(self) -> list[pl.DataFrame]:
@@ -47,7 +47,7 @@ def by_first_letter_of_column_values(self, col: str) -> list[pl.DataFrame]:
 def test_custom_expr_namespace() -> None:
     @pl.api.register_expr_namespace("power")
     class PowersOfN:
-        def __init__(self, expr: pl.Expr):
+        def __init__(self, expr: pl.Expr) -> None:
             self._expr = expr
 
         def next(self, p: int) -> pl.Expr:
@@ -76,7 +76,7 @@ def nearest(self, p: int) -> pl.Expr:
 def test_custom_lazy_namespace() -> None:
     @pl.api.register_lazyframe_namespace("split")
     class SplitFrame:
-        def __init__(self, lf: pl.LazyFrame):
+        def __init__(self, lf: pl.LazyFrame) -> None:
             self._lf = lf
 
         def by_column_dtypes(self) -> list[pl.LazyFrame]:
@@ -109,7 +109,7 @@ def by_column_dtypes(self) -> list[pl.LazyFrame]:
 def test_custom_series_namespace() -> None:
     @pl.api.register_series_namespace("math")
     class CustomMath:
-        def __init__(self, s: pl.Series):
+        def __init__(self, s: pl.Series) -> None:
             self._s = s
 
         def square(self) -> pl.Series:
@@ -151,19 +151,19 @@ def test_namespace_cannot_override_builtin() -> None:
 
         @pl.api.register_dataframe_namespace("dt")
         class CustomDt:
-            def __init__(self, df: pl.DataFrame):
+            def __init__(self, df: pl.DataFrame) -> None:
                 self._df = df
 
 
 def test_namespace_warning_on_override() -> None:
     @pl.api.register_dataframe_namespace("math")
     class CustomMath:
-        def __init__(self, df: pl.DataFrame):
+        def __init__(self, df: pl.DataFrame) -> None:
             self._df = df
 
     with pytest.raises(UserWarning):
 
         @pl.api.register_dataframe_namespace("math")
         class CustomMath2:
-            def __init__(self, df: pl.DataFrame):
+            def __init__(self, df: pl.DataFrame) -> None:
                 self._df = df
diff --git a/py-polars/tests/unit/test_config.py b/py-polars/tests/unit/test_config.py
index e4f1a152ad7b..f6cd9411bebf 100644
--- a/py-polars/tests/unit/test_config.py
+++ b/py-polars/tests/unit/test_config.py
@@ -123,7 +123,7 @@ def test_set_tbl_rows() -> None:
         "│ …   ┆ …   ┆ …   │\n"
         "└─────┴─────┴─────┘"
     )
-    assert str(ser) == "shape: (5,)\n" "Series: 'ser' [i64]\n" "[\n" "\t…\n" "]"
+    assert str(ser) == "shape: (5,)\nSeries: 'ser' [i64]\n[\n\t…\n]"
 
     pl.Config.set_tbl_rows(1)
     assert (
@@ -137,7 +137,7 @@ def test_set_tbl_rows() -> None:
         "│ …   ┆ …   ┆ …   │\n"
         "└─────┴─────┴─────┘"
     )
-    assert str(ser) == "shape: (5,)\n" "Series: 'ser' [i64]\n" "[\n" "\t1\n" "\t…\n" "]"
+    assert str(ser) == "shape: (5,)\nSeries: 'ser' [i64]\n[\n\t1\n\t…\n]"
 
     pl.Config.set_tbl_rows(2)
     assert (
@@ -479,7 +479,7 @@ def test_shape_format_for_big_numbers() -> None:
 
     pl.Config.set_tbl_rows(0)
     ser = pl.Series("ser", range(1000))
-    assert str(ser) == "shape: (1_000,)\n" "Series: 'ser' [i64]\n" "[\n" "\t…\n" "]"
+    assert str(ser) == "shape: (1_000,)\nSeries: 'ser' [i64]\n[\n\t…\n]"
 
     pl.Config.set_tbl_rows(1)
     pl.Config.set_tbl_cols(1)
diff --git a/py-polars/tests/unit/test_cse.py b/py-polars/tests/unit/test_cse.py
index c4b6466e51b7..6874512e6133 100644
--- a/py-polars/tests/unit/test_cse.py
+++ b/py-polars/tests/unit/test_cse.py
@@ -148,13 +148,7 @@ def test_cse_9630() -> None:
 @pytest.mark.write_disk
 def test_schema_row_index_cse() -> None:
     csv_a = NamedTemporaryFile()
-    csv_a.write(
-        b"""
-A,B
-Gr1,A
-Gr1,B
-    """.strip()
-    )
+    csv_a.write(b"A,B\nGr1,A\nGr1,B")
     csv_a.seek(0)
 
     df_a = pl.scan_csv(csv_a.name).with_row_index("Idx")
@@ -166,8 +160,6 @@ def test_schema_row_index_cse() -> None:
         .collect(comm_subexpr_elim=True)
     )
 
-    csv_a.close()
-
     expected = pl.DataFrame(
         {
             "A": ["Gr1"],
diff --git a/py-polars/tests/unit/test_format.py b/py-polars/tests/unit/test_format.py
index 8f69d62fcaee..2461f100209b 100644
--- a/py-polars/tests/unit/test_format.py
+++ b/py-polars/tests/unit/test_format.py
@@ -81,7 +81,7 @@ def test_fmt_series(
     s = pl.Series(name="foo", values=values)
     with pl.Config(fmt_str_lengths=15):
         print(s)
-    out, err = capfd.readouterr()
+    out, _err = capfd.readouterr()
     assert out == expected
 
 
@@ -246,7 +246,7 @@ def test_fmt_unsigned_int_thousands_sep(
 def test_fmt_float(capfd: pytest.CaptureFixture[str]) -> None:
     s = pl.Series(name="foo", values=[7.966e-05, 7.9e-05, 8.4666e-05, 8.00007966])
     print(s)
-    out, err = capfd.readouterr()
+    out, _err = capfd.readouterr()
     expected = """shape: (4,)
 Series: 'foo' [f64]
 [