如何使用C#編寫關聯規則挖掘演算法

List<List<string>> dataset = new List<List<string>>();
dataset.Add(new List<string> { "A", "B", "C" });
dataset.Add(new List<string> { "A", "B", "D" });
dataset.Add(new List<string> { "B", "C", "D" });
// ...

Dictionary<List<string>, int> candidateItemsets = new Dictionary<List<string>, int>();

// 生成候选项集
foreach (List<string> transaction in dataset)
{
    foreach (string item in transaction)
    {
        List<string> candidate = new List<string> { item };
        if (candidateItemsets.ContainsKey(candidate))
        {
            candidateItemsets[candidate]++;
        }
        else
        {
            candidateItemsets.Add(candidate, 1);
        }
    }
}

List<List<string>> frequentItemsets = new List<List<string>>();
int supportThreshold = 2; // 设置支持度阈值

// 筛选频繁项集
foreach (var itemset in candidateItemsets)
{
    if (itemset.Value >= supportThreshold)
    {
        frequentItemsets.Add(itemset.Key);
    }
}

List<Tuple<List<string>, List<string>>> associationRules = new List<Tuple<List<string>, List<string>>>();
double confidenceThreshold = 0.5; // 设置置信度阈值

// 生成关联规则
foreach (var frequentItemset in frequentItemsets)
{
    int itemsetLength = frequentItemset.Count;
    for (int i = 1; i < itemsetLength; i++)
    {
        List<List<string>> combinations = GetCombinations(frequentItemset, i);
        foreach (var combination in combinations)
        {
            List<string> remainingItems = frequentItemset.Except(combination).ToList();
            double confidence = (double)candidateItemsets[frequentItemset] / candidateItemsets[combination];
            if (confidence >= confidenceThreshold)
            {
                associationRules.Add(new Tuple<List<string>, List<string>>(combination, remainingItems));
            }
        }
    }
}

public List<List<string>> GetCombinations(List<string> items, int length)
{
    List<List<string>> combinations = new List<List<string>>();
    Combine(items, length, 0, new List<string>(), combinations);
    return combinations;
}

private void Combine(List<string> items, int length, int start, List<string> currentCombination, List<List<string>> combinations)
{
    if (length == 0)
    {
        combinations.Add(new List<string>(currentCombination));
        return;
    }
    if (start == items.Count)
    {
        return;
    }
    currentCombination.Add(items[start]);
    Combine(items, length - 1, start + 1, currentCombination, combinations);
    currentCombination.RemoveAt(currentCombination.Count - 1);
    Combine(items, length, start + 1, currentCombination, combinations);
}