要使用纯python写
时间: 2024-12-14 19:24:44 浏览: 3
如果您需要使用纯Python编写代码来完成《大数据分析方法》实验报告中的任务,以下是一些关键步骤和技术要点:
### 实验一:关联规则算法实验
#### 目标
使用Apriori算法发现蔬菜价格的相关性。
#### 步骤
1. **数据预处理**
- 读取CSV文件,处理缺失值。
- 将数据转换为适合Apriori算法的格式。
2. **实现Apriori算法**
- 计算频繁项集。
- 生成关联规则。
3. **结果分析**
- 解释发现的关联规则,分析蔬菜价格的同涨、同跌或涨跌不同步现象。
#### 示例代码
```python
import csv
from collections import defaultdict
def load_data(file_path):
transactions = []
with open(file_path, 'r') as file:
reader = csv.DictReader(file)
for row in reader:
transaction = [row['蔬菜名'], row['价格']]
if all(transaction): # 过滤掉有空值的行
transactions.append(transaction)
return transactions
def apriori(transactions, min_support=0.5):
def generate_candidates(itemsets, k):
candidates = set()
for itemset in itemsets:
for other_itemset in itemsets:
candidate = itemset.union(other_itemset)
if len(candidate) == k and candidate not in candidates:
candidates.add(frozenset(candidate))
return candidates
def prune(candidates, prev_freq_itemsets, k):
pruned_candidates = set()
for candidate in candidates:
subsets = [frozenset(x) for x in combinations(candidate, k-1)]
if all(subset in prev_freq_itemsets for subset in subsets):
pruned_candidates.add(candidate)
return pruned_candidates
from itertools import combinations
C1 = {frozenset([item]) for transaction in transactions for item in transaction}
L1 = {item: sum(1 for t in transactions if item.issubset(t)) / len(transactions) for item in C1}
Lk = {item for item, support in L1.items() if support >= min_support}
freq_itemsets = list(Lk)
k = 2
while True:
Ck = generate_candidates(Lk, k)
Ck = prune(Ck, Lk, k)
Lk = {item: sum(1 for t in transactions if item.issubset(t)) / len(transactions) for item in Ck}
Lk = {item for item, support in Lk.items() if support >= min_support}
if not Lk:
break
freq_itemsets.extend(Lk)
k += 1
return freq_itemsets
def generate_rules(freq_itemsets, min_confidence=0.7):
rules = []
for itemset in freq_itemsets:
for i in range(1, len(itemset)):
for antecedent in combinations(itemset, i):
antecedent = frozenset(antecedent)
consequent = itemset.difference(antecedent)
confidence = support[frozenset(itemset)] / support[antecedent]
if confidence >= min_confidence:
rules.append((antecedent, consequent, confidence))
return rules
# 加载数据
transactions = load_data('vegetable_prices.csv')
# 计算频繁项集
freq_itemsets = apriori(transactions)
# 生成关联规则
rules = generate_rules(freq_itemsets)
# 打印结果
for rule in rules:
print(f"Rule: {rule[0]} -> {rule[1]}, Confidence: {rule[2]:.2f}")
```
### 其他实验
对于其他实验(如回归算法、分类算法、聚类算法),您可以参照类似的步骤:
1. **数据预处理**:读取数据,处理缺失值,标准化或归一化数据。
2. **算法实现**:选择合适的算法并实现。
3. **结果分析**:解释模型的性能和结果。
如果您需要更详细的代码示例或其他帮助,请告诉我具体的需求。
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