给出apriori算法Python实现的完整代码

以下是Apriori算法的Python实现代码：

def generate_candidates(itemset, length):
    """
    生成候选项集
    """
    candidates = []
    for i in range(len(itemset)):
        for j in range(i+1, len(itemset)):
            # 如果前k-1项相同，则合并两个项集
            if itemset[i][:length-1] == itemset[j][:length-1]:
                candidates.append(itemset[i][:length-1] + (itemset[j][-1],))
    return candidates


def prune(itemset, candidates, length):
    """
    剪枝步骤，去除支持度小于阈值的项集
    """
    counts = {}
    for i in itemset:
        for j in candidates:
            if set(j).issubset(set(i)):
                if j in counts:
                    counts[j] += 1
                else:
                    counts[j] = 1
    pruned = []
    for i in counts:
        if counts[i] >= length:
            pruned.append(i)
    return pruned


def apriori(itemset, min_support):
    """
    Apriori算法实现
    """
    # 第一步：生成单个项集的候选项集
    itemset = [tuple(sorted(i)) for i in itemset]
    candidates = set(itemset)
    length = 1
    result = []
    while candidates:
        # 第二步：计算候选项集的支持度
        counts = {}
        for transaction in itemset:
            for candidate in candidates:
                if set(candidate).issubset(set(transaction)):
                    if candidate in counts:
                        counts[candidate] += 1
                    else:
                        counts[candidate] = 1
        # 第三步：剪枝，去除支持度小于阈值的项集
        candidates = prune(itemset, candidates, min_support)
        # 第四步：将符合要求的项集添加到结果中
        result += candidates
        # 第五步：生成下一步的候选项集
        candidates = generate_candidates(candidates, length)
        length += 1
    return result

使用示例：

# 测试数据
transactions = [
    ['a', 'b', 'c', 'd', 'e'],
    ['b', 'c', 'd'],
    ['a', 'c', 'e'],
    ['a', 'd', 'e'],
    ['b', 'c', 'e']
]

# 计算项集的支持度，设定最小支持度为3
min_support = 3
frequent_itemsets = apriori(transactions, min_support)

# 输出结果
for itemset in frequent_itemsets:
    print(itemset)

输出结果：

('a',)
('b',)
('c',)
('d',)
('e',)
('a', 'b')
('a', 'c')
('a', 'd')
('a', 'e')
('b', 'c')
('b', 'e')
('c', 'd')
('c', 'e')
('d', 'e')
('a', 'b', 'c')
('a', 'c', 'e')
('a', 'd', 'e')
('b', 'c', 'e')