学点算法搞安全之apriori

def createC1(dataSet):
   C1 = []
   for transaction in dataSet:
       for item in transaction:
           if [item] not in C1:
               C1.append([item])
   C1.sort()
   return map(frozenset, C1)
def scanD(D, Ck, minSupport):
   ssCnt = {}
   for tid in D:
       for can in Ck:
           if can.issubset(tid):
               ssCnt[can] = ssCnt.get(can, 0) + 1
   numItems = float(len(D))
   retList = []
   supportData = {}
   for key in ssCnt:
       support = ssCnt[key] / numItems
       if support >= minSupport:
           retList.insert(0, key)
       supportData[key] = support
   return retList, supportData
def aprioriGen(Lk, k):
   retList = []
   lenLk = len(Lk)
   for i in range(lenLk):
       for j in range(i + 1, lenLk):
           L1 = list(Lk[i])[: k - 2];
           L2 = list(Lk[j])[: k - 2];
           L1.sort();
           L2.sort()
           if L1 == L2:
               retList.append(Lk[i] | Lk[j])
   return retList
def apriori(dataSet, minSupport=0.5):
   C1 = createC1(dataSet)
   D = map(set, dataSet)
   L1, suppData = scanD(D, C1, minSupport)
   L = [L1]
   k = 2
   while (len(L[k - 2]) > 0):
       Ck = aprioriGen(L[k - 2], k)
       Lk, supK = scanD(D, Ck, minSupport)
       suppData.update(supK)
       L.append(Lk)
       k += 1
   return L, suppData
def calcConf(freqSet, H, supportData, brl, minConf=0.7):
   prunedH = []
   for conseq in H:
       conf = supportData[freqSet] / supportData[freqSet - conseq]
       if conf >= minConf:
           print freqSet - conseq, ‘-->‘, conseq, ‘conf:‘, conf
           brl.append((freqSet - conseq, conseq, conf))
           prunedH.append(conseq)
   return prunedH
def rulesFromConseq(freqSet, H, supportData, brl, minConf=0.7):
   m = len(H[0])
   if len(freqSet) > m + 1:
       Hmp1 = aprioriGen(H, m + 1)
       Hmp1 = calcConf(freqSet, Hmp1, supportData, brl, minConf)
       if len(Hmp1) > 1:
           rulesFromConseq(freqSet, Hmp1, supportData, brl, minConf)
def generateRules(L, supportData, minConf=0.7):
   bigRuleList = []
   for i in range(1, len(L)):
       for freqSet in L[i]:
           H1 = [frozenset([item]) for item in freqSet]
           if i > 1:
               rulesFromConseq(freqSet, H1, supportData, bigRuleList, minConf)
           else:
               calcConf(freqSet, H1, supportData, bigRuleList, minConf)
   return bigRuleList