(2)使用python实现Apriori算法中的频繁项集生成过程,并使用上述数据集输出频繁项集。
时间: 2024-03-08 16:45:54 浏览: 160
以下是Python中使用Apriori算法实现频繁项集生成过程的代码示例,使用的数据集与上述代码示例相同:
```python
# 导入相关库
import pandas as pd
from itertools import combinations
# 读取数据集
data = pd.read_excel('data.xlsx')
# 将数据集转换为适合进行关联分析的格式
def encode_units(x):
if x <= 0:
return 0
if x >= 1:
return 1
data = data.applymap(encode_units)
# 定义函数生成候选项集
def generate_candidate_set(data):
candidate_set = []
for i in range(len(data.columns)):
col = data.iloc[:, i]
for j in range(i+1, len(data.columns)):
next_col = data.iloc[:, j]
candidate = list(col.index & next_col.index)
candidate_set.append([candidate, i, j])
return candidate_set
# 定义函数验证候选项集是否满足支持度要求
def check_support(candidate_set, data, min_support):
support = []
for candidate in candidate_set:
count = 0
for index, row in data.iterrows():
if set(candidate[0]).issubset(set(row.index)):
count += 1
support.append(count)
support = [sup/len(data) for sup in support]
frequent_set = [candidate_set[i] for i in range(len(candidate_set)) if support[i] >= min_support]
return frequent_set, support
# 定义函数生成频繁项集
def generate_frequent_set(data, min_support):
candidate_set = generate_candidate_set(data)
frequent_set, support = check_support(candidate_set, data, min_support)
while len(candidate_set) > 0:
candidate_set = generate_candidate_set(pd.DataFrame([set(freq[0]) for freq in frequent_set]))
new_frequent_set, new_support = check_support(candidate_set, data, min_support)
frequent_set += new_frequent_set
support += new_support
frequent_set = pd.DataFrame(frequent_set, columns=['itemset', 'col1', 'col2'])
frequent_set['support'] = support
frequent_set['length'] = frequent_set['itemset'].apply(len)
return frequent_set
# 执行频繁项集生成过程
frequent_itemsets = generate_frequent_set(data, min_support=0.05)
# 输出频繁项集
print(frequent_itemsets)
```
其中,`generate_candidate_set`函数生成候选项集,`check_support`函数验证候选项集是否满足支持度要求,`generate_frequent_set`函数生成频繁项集。最后,使用`generate_frequent_set`函数获取频繁项集,并输出结果。
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