pageRank---python实现

def calculatepagerank(self,iterations=20):
    #清除当前的PageRank表
    self.con.execute(‘drop table if exists pagerank‘)
    self.con.execute(‘create table pagerank(urlid primary key,score)‘)
    
    #初始化每个url，令其pagerank值为1
    self.con.execute(‘insert into pagerank select rowid, 1.0 from urllist‘)
    self.dbcommit()
    for i in range(iterations):
        print ‘Iteration%d‘%(i)
        for (urlid,) in self.con.execute(‘select rowid from urllist‘):
            pr=0.15
            #循环遍历指向当前网页的所有其他网页
            for (linker,) in self.con.execute(‘select distinct fromid from link            where toid=%d‘%urlid):
                linkingpr=self.con.execute(‘select score from pagerank where urlid=%d‘%linker).fetchone()[0]
                pr+=0.85*(linkingpr/linkingcount)
                self.con.execute(‘update pagerank set score=%f where urlid=%d‘%(pr,urlid))
            self.dbcommit()