python映射关系

有关系A和B的文件，其中A-->B，B有可能也是A的成员，寻找一个tree，如果B已经到达最顶层，那么A-->B为正确的映射关系，如果出现循环则记录这些错误，和key的最终指向

#-*-coding:UTF-8-*-#!/usr/bin/env python__author__ = 'chao.zhang.sh'import threadingclass Mapping():    def __init__(self):        self.Mapping={}        self.LastMerge={}        self.keys=None    def Search(self):        try:            DataFile=open('mapping.csv','r')            DataWrite=open('Result/mappingResult.csv','w')            DataWriteCircle=open('Result/mappingResultWrong.csv','a')            A=[]            B=[]            DataFile.next()            for temp in DataFile:                data=temp.decode("utf-8").strip().split("\t")                self.Mapping[data[1]]=data[2]                A.append(data[1])                B.append(data[2])            self.keys=self.Mapping.keys()            for temp in (set(B).difference(set(A)))://求第二列和第一列的差集                self.Mapping[temp]=int(-1)//将差集全部置-1            print len(self.Mapping)            i=0            for key in self.keys:                i+=1                j=0                Keys=[key]                while True:                    if int(self.Mapping[Keys[-1]])==int(-1)://遇到-1，证明已经找到树顶部                        DataWrite.write("\t".join([key,Keys[-1]]).encode("utf-8")+"\n")                        break//跳出while循环                    else:                        if self.Mapping[Keys[-1]] in Keys://遇到新的key值出现在keys列表中，证明出现了循环，记录错误数据                            DataWriteCircle.write("\t".join(Keys).encode("utf-8")+"\n")                            break                     Keys.append(self.Mapping[Keys[-1]])                        print "key:%s newKey:%s"%(key,Keys[-1])                print i        except Exception as err:            print err        finally:            DataFile.close()            DataWrite.flush()            DataWrite.close()            DataWriteCircle.flush()            DataWriteCircle.close()   if "__main__"==__name__:    A=Mapping()    A.Search()