# skfolio.utils.stats.sample_unique_subsets ### skfolio.utils.stats.sample_unique_subsets(n, k, n_subsets, random_state=None) Generate unique k-element subsets from a universe of size n using combinatorial unranking. Each subset is drawn without replacement (elements within subset are distinct) and no subset is repeated across draws. Ranks are sampled uniformly without replacement over [0, C(n, k)). Time complexity: O(n_subsets \* k) Space complexity: O(n_subsets \* k) * **Parameters:** **n** *int* : Universe size. **k** *int* : Subset size (0 <= k <= n). **n_subsets** *int* : Number of distinct subsets to generate (0 <= n_subsets <= C(n, k)). **random_state** *int, RandomState instance, optional* : Seed or random state to ensure reproducibility. * **Returns:** **subsets** *ndarray of shape (n_subsets, k)* : 2D integer array of shape (n_subsets, k) where each row is a sorted k-combination. * **Raises:** ValueError : If any parameters are out of valid ranges.