Apriori算法--Python实现

 1 # -*- coding: utf-8 -*-
 2 """
 3 Created on Mon Nov 05 22:50:13 2018
 4 
 5 @author: ZhuChaochao
 6 """
 7 def loadDataSet():
 8     f = open("F:/Python CODE/zcc/1.txt",‘r‘) #读取的数据
 9     source = f.readlines()
10     f.close()
11     dataset = []
12     for line in source:
13         line=line.strip().split(‘  ‘)
14         curLine = list(map(int,line))
15         dataset.append(curLine)
16     return dataset
17 
18 
19 def createC1(dataset):
20     C1 = []
21     for transaction in dataset:
22         for item in transaction:
23             if not [item] in C1:
24                 C1.append([item])
25     C1.sort()
26     return map(frozenset,C1)
27 
28 def scanD(D,CK,minSupport):
29     ssCnt = {}
30     for tid in D:
31         for can in CK:
32             if can.issubset(tid):
33                 if not can in ssCnt:
34                     ssCnt[can] = 1
35                 else:
36                     ssCnt[can] += 1
37     
38     D=list(map(set,D))
39     numItems = float(len(D))
40     retList = []
41     supportData = {}
42     for key in ssCnt:
43         try:
44             support = ssCnt[key]/numItems
45         except (ZeroDivisionError,ValueError) as e:
46             print(e)
47         if support >= minSupport:
48             retList.insert(0,key)
49         supportData[key] = support
50     return retList,supportData
51 
52 def aprioriGen(Lk, k): 
53     retList = []
54     lenLk = len(Lk)
55     for i in range(lenLk):
56         for j in range(i+1, lenLk): 
57             L1 = list(Lk[i])[:k-2]; L2 = list(Lk[j])[:k-2]
58             L1.sort(); L2.sort()
59             if L1==L2: 
60                 retList.append(Lk[i] | Lk[j]) 
61     return retList
62 
63 def apriori(dataSet, minSupport = 0.5):
64     C1 = createC1(dataSet)
65     D = map(set, dataSet)
66     L1, supportData = scanD(D, C1, minSupport)
67     L = [L1]
68     k = 2
69     while (len(L[k-2]) > 0):
70         Ck = aprioriGen(L[k-2], k)
71         Lk, supK = scanD(D, Ck, minSupport)
72         supportData.update(supK)
73         L.append(Lk)
74         k += 1
75     L, supportDatareturn