speed up fix

Author: amalia-k510

src/fast_array_utils/stats/_mean_var.py

@@ -35,11 +35,16 @@ def mean_var_(
 
     from . import mean
 
-    if array_api_compat.is_array_api_obj(x):
-        xp = array_api_compat.array_namespace(x)
-        float64 = xp.float64
-    else:
+    if isinstance(x, np.ndarray | types.CSBase):
         float64 = np.float64
+    else:
+        import array_api_compat
+
+        if array_api_compat.is_array_api_obj(x):
+            xp = array_api_compat.array_namespace(x)
+            float64 = xp.float64
+        else:
+            float64 = np.float64
 
     if axis is not None and isinstance(x, types.CSBase):
         mean_, var = _sparse_mean_var(x, axis=axis)

src/fast_array_utils/stats/_power.py

@@ -27,7 +27,7 @@ def power[Arr: Array](x: Arr, n: int, /, dtype: DTypeLike | None = None) -> Arr:
 
 
 @singledispatch
-def _power(x: Array, n: int, /, dtype: DTypeLike | None = None) -> Any:
+def _power(x: Array, n: int, /, dtype: DTypeLike | None = None) -> Any:  # noqa: ANN401
     if TYPE_CHECKING:
         assert not isinstance(x, types.DaskArray | types.CSBase | types.CupyCSMatrix)