list-comprehensionify

narwhals-dev · Jan 26, 2025 · 5ee6009 · 5ee6009
1 parent b780de5
commit 5ee6009
Showing 1 changed file with 6 additions and 21 deletions.
diff --git a/narwhals/_polars/namespace.py b/narwhals/_polars/namespace.py
@@ -35,8 +35,6 @@ def __init__(
         self._version = version
 
     def __getattr__(self: Self, attr: str) -> Any:
-        import polars as pl
-
         from narwhals._polars.expr import PolarsExpr
 
         def func(*args: Any, **kwargs: Any) -> Any:
@@ -50,8 +48,6 @@ def func(*args: Any, **kwargs: Any) -> Any:
         return func
 
     def nth(self: Self, *indices: int) -> PolarsExpr:
-        import polars as pl
-
         from narwhals._polars.expr import PolarsExpr
 
         if self._backend_version < (1, 0, 0):
@@ -62,8 +58,6 @@ def nth(self: Self, *indices: int) -> PolarsExpr:
         )
 
     def len(self: Self) -> PolarsExpr:
-        import polars as pl
-
         from narwhals._polars.expr import PolarsExpr
 
         if self._backend_version < (0, 20, 5):
@@ -114,8 +108,6 @@ def concat(
         )
 
     def lit(self: Self, value: Any, dtype: DType | None) -> PolarsExpr:
-        import polars as pl
-
         from narwhals._polars.expr import PolarsExpr
 
         if dtype is not None:
@@ -129,8 +121,6 @@ def lit(self: Self, value: Any, dtype: DType | None) -> PolarsExpr:
         )
 
     def mean_horizontal(self: Self, *exprs: IntoPolarsExpr) -> PolarsExpr:
-        import polars as pl
-
         from narwhals._polars.expr import PolarsExpr
 
         polars_exprs = cast("list[PolarsExpr]", parse_into_exprs(*exprs, namespace=self))
@@ -155,8 +145,6 @@ def concat_str(
         separator: str,
         ignore_nulls: bool,
     ) -> PolarsExpr:
-        import polars as pl
-
         from narwhals._polars.expr import PolarsExpr
 
         pl_exprs: list[pl.Expr] = [
@@ -215,17 +203,14 @@ def __init__(self: Self, version: Version, backend_version: tuple[int, ...]) ->
         self._backend_version = backend_version
 
     def by_dtype(self: Self, dtypes: Iterable[DType]) -> PolarsExpr:
-        import polars as pl
-
         from narwhals._polars.expr import PolarsExpr
 
-        native_dtypes: list[pl.DataType | type[pl.DataType]] = []
-        for dtype in dtypes:
-            native_dtype_instantiated = narwhals_to_native_dtype(dtype, self._version)
-            if isinstance(dtype, type) and issubclass(dtype, DType):
-                native_dtypes.append(native_dtype_instantiated.__class__)
-            else:
-                native_dtypes.append(native_dtype_instantiated)
+        native_dtypes = [
+            narwhals_to_native_dtype(dtype, self._version).__class__
+            if isinstance(dtype, type) and issubclass(dtype, DType)
+            else narwhals_to_native_dtype(dtype, self._version)
+            for dtype in dtypes
+        ]
         return PolarsExpr(
             pl.selectors.by_dtype(native_dtypes),
             version=self._version,