如何获得给定数量的层变体的唯一组合，同时使用Python维护每个层变体的给定比例？

import itertools

def get_unique_combinations(num_variants, ratios):
    # 创建层变体列表
    variants = list(range(num_variants))

    # 计算每个层变体的数量
    total_count = sum(ratios)
    counts = [int(ratio / total_count * num_variants) for ratio in ratios]

    # 生成唯一组合
    combinations = set()
    for r in range(1, num_variants + 1):
        for combo in itertools.combinations(variants, r):
            if len(combo) == sum(counts):
                combinations.add(combo)

    # 维护比例
    valid_combinations = []
    for combo in combinations:
        combo_counts = [combo.count(variant) for variant in variants]
        if combo_counts == counts:
            valid_combinations.append(combo)

    return valid_combinations

# 示例用法
num_variants = 3
ratios = [40, 30, 30]
combinations = get_unique_combinations(num_variants, ratios)
print(combinations)