我正在使用 python 2.7.8 。我所遵循的代码来自Book name为“编程集体智慧O Reilly by Toby Segaram”第4章：我不知道为什么这个错误即将发生或者作者犯了一些错误？我也试图找到pysqlite2但失败了。知道为什么会出现这个问题吗？
这是代码：
import urllib2
from BeautifulSoup import *
from urlparse import urljoin
from pysqlite2 import dbapi2 as sqlite
import nn
mynet=nn.searchnet('nn.db')
# Create a list of words to ignore
ignorewords={'the':1,'of':1,'to':1,'and':1,'a':1,'in':1,'is':1,'it':1}
class crawler:
# Initialize the crawler with the name of database
def __init__(self,dbname):
self.con=sqlite.connect(dbname)
def __del__(self):
self.con.close()
def dbcommit(self):
self.con.commit()
# Auxilliary function for getting an entry id and adding
# it if it's not present
def getentryid(self,table,field,value,createnew=True):
cur=self.con.execute(
"select rowid from %s where %s='%s'" % (table,field,value))
res=cur.fetchone()
if res==None:
cur=self.con.execute(
"insert into %s (%s) values ('%s')" % (table,field,value))
return cur.lastrowid
else:
return res[0]
# Index an individual page
def addtoindex(self,url,soup):
if self.isindexed(url): return
print 'Indexing '+url
# Get the individual words
text=self.gettextonly(soup)
words=self.separatewords(text)
# Get the URL id
urlid=self.getentryid('urllist','url',url)
# Link each word to this url
for i in range(len(words)):
word=words[i]
if word in ignorewords: continue
wordid=self.getentryid('wordlist','word',word)
self.con.execute("insert into wordlocation(urlid,wordid,location) values (%d,%d,%d)" % (urlid,wordid,i))
# Extract the text from an HTML page (no tags)
def gettextonly(self,soup):
v=soup.string
if v==Null:
c=soup.contents
resulttext=''
for t in c:
subtext=self.gettextonly(t)
resulttext+=subtext+'\n'
return resulttext
else:
return v.strip()
# Seperate the words by any non-whitespace character
def separatewords(self,text):
splitter=re.compile('\\W*')
return [s.lower() for s in splitter.split(text) if s!='']
# Return true if this url is already indexed
def isindexed(self,url):
return False
# Add a link between two pages
def addlinkref(self,urlFrom,urlTo,linkText):
words=self.separateWords(linkText)
fromid=self.getentryid('urllist','url',urlFrom)
toid=self.getentryid('urllist','url',urlTo)
if fromid==toid: return
cur=self.con.execute("insert into link(fromid,toid) values (%d,%d)" % (fromid,toid))
linkid=cur.lastrowid
for word in words:
if word in ignorewords: continue
wordid=self.getentryid('wordlist','word',word)
self.con.execute("insert into linkwords(linkid,wordid) values (%d,%d)" % (linkid,wordid))
# Starting with a list of pages, do a breadth
# first search to the given depth, indexing pages
# as we go
def crawl(self,pages,depth=2):
for i in range(depth):
newpages={}
for page in pages:
try:
c=urllib2.urlopen(page)
except:
print "Could not open %s" % page
continue
try:
soup=BeautifulSoup(c.read())
self.addtoindex(page,soup)
links=soup('a')
for link in links:
if ('href' in dict(link.attrs)):
url=urljoin(page,link['href'])
if url.find("'")!=-1: continue
url=url.split('#')[0] # remove location portion
if url[0:4]=='http' and not self.isindexed(url):
newpages[url]=1
linkText=self.gettextonly(link)
self.addlinkref(page,url,linkText)
self.dbcommit()
except:
print "Could not parse page %s" % page
pages=newpages
# Create the database tables
def createindextables(self):
self.con.execute('create table urllist(url)')
self.con.execute('create table wordlist(word)')
self.con.execute('create table wordlocation(urlid,wordid,location)')
self.con.execute('create table link(fromid integer,toid integer)')
self.con.execute('create table linkwords(wordid,linkid)')
self.con.execute('create index wordidx on wordlist(word)')
self.con.execute('create index urlidx on urllist(url)')
self.con.execute('create index wordurlidx on wordlocation(wordid)')
self.con.execute('create index urltoidx on link(toid)')
self.con.execute('create index urlfromidx on link(fromid)')
self.dbcommit()
def calculatepagerank(self,iterations=20):
# clear out the current page rank tables
self.con.execute('drop table if exists pagerank')
self.con.execute('create table pagerank(urlid primary key,score)')
# initialize every url with a page rank of 1
for (urlid,) in self.con.execute('select rowid from urllist'):
self.con.execute('insert into pagerank(urlid,score) values (%d,1.0)' % urlid)
self.dbcommit()
for i in range(iterations):
print "Iteration %d" % (i)
for (urlid,) in self.con.execute('select rowid from urllist'):
pr=0.15
# Loop through all the pages that link to this one
for (linker,) in self.con.execute(
'select distinct fromid from link where toid=%d' % urlid):
# Get the page rank of the linker
linkingpr=self.con.execute(
'select score from pagerank where urlid=%d' % linker).fetchone()[0]
# Get the total number of links from the linker
linkingcount=self.con.execute(
'select count(*) from link where fromid=%d' % linker).fetchone()[0]
pr+=0.85*(linkingpr/linkingcount)
self.con.execute(
'update pagerank set score=%f where urlid=%d' % (pr,urlid))
self.dbcommit()
class searcher:
def __init__(self,dbname):
self.con=sqlite.connect(dbname)
def __del__(self):
self.con.close()
def getmatchrows(self,q):
# Strings to build the query
fieldlist='w0.urlid'
tablelist=''
clauselist=''
wordids=[]
# Split the words by spaces
words=q.split(' ')
tablenumber=0
for word in words:
# Get the word ID
wordrow=self.con.execute(
"select rowid from wordlist where word='%s'" % word).fetchone()
if wordrow!=None:
wordid=wordrow[0]
wordids.append(wordid)
if tablenumber>0:
tablelist+=','
clauselist+=' and '
clauselist+='w%d.urlid=w%d.urlid and ' % (tablenumber-1,tablenumber)
fieldlist+=',w%d.location' % tablenumber
tablelist+='wordlocation w%d' % tablenumber
clauselist+='w%d.wordid=%d' % (tablenumber,wordid)
tablenumber+=1
# Create the query from the separate parts
fullquery='select %s from %s where %s' % (fieldlist,tablelist,clauselist)
print fullquery
cur=self.con.execute(fullquery)
rows=[row for row in cur]
return rows,wordids
def getscoredlist(self,rows,wordids):
totalscores=dict([(row[0],0) for row in rows])
# This is where we'll put our scoring functions
weights=[(1.0,self.locationscore(rows)),
(1.0,self.frequencyscore(rows)),
(1.0,self.pagerankscore(rows)),
(1.0,self.linktextscore(rows,wordids)),
(5.0,self.nnscore(rows,wordids))]
for (weight,scores) in weights:
for url in totalscores:
totalscores[url]+=weight*scores[url]
return totalscores
def geturlname(self,id):
return self.con.execute(
"select url from urllist where rowid=%d" % id).fetchone()[0]
def query(self,q):
rows,wordids=self.getmatchrows(q)
scores=self.getscoredlist(rows,wordids)
rankedscores=[(score,url) for (url,score) in scores.items()]
rankedscores.sort()
rankedscores.reverse()
for (score,urlid) in rankedscores[0:10]:
print '%f\t%s' % (score,self.geturlname(urlid))
return wordids,[r[1] for r in rankedscores[0:10]]
def normalizescores(self,scores,smallIsBetter=0):
vsmall=0.00001 # Avoid division by zero errors
if smallIsBetter:
minscore=min(scores.values())
return dict([(u,float(minscore)/max(vsmall,l)) for (u,l) in scores.items()])
else:
maxscore=max(scores.values())
if maxscore==0: maxscore=vsmall
return dict([(u,float(c)/maxscore) for (u,c) in scores.items()])
def frequencyscore(self,rows):
counts=dict([(row[0],0) for row in rows])
for row in rows: counts[row[0]]+=1
return self.normalizescores(counts)
def locationscore(self,rows):
locations=dict([(row[0],1000000) for row in rows])
for row in rows:
loc=sum(row[1:])
if loc<locations[row[0]]: locations[row[0]]=loc
return self.normalizescores(locations,smallIsBetter=1)
def distancescore(self,rows):
# If there's only one word, everyone wins!
if len(rows[0])<=2: return dict([(row[0],1.0) for row in rows])
# Initialize the dictionary with large values
mindistance=dict([(row[0],1000000) for row in rows])
for row in rows:
dist=sum([abs(row[i]-row[i-1]) for i in range(2,len(row))])
if dist<mindistance[row[0]]: mindistance[row[0]]=dist
return self.normalizescores(mindistance,smallIsBetter=1)
def inboundlinkscore(self,rows):
uniqueurls=dict([(row[0],1) for row in rows])
inboundcount=dict([(u,self.con.execute('select count(*) from link where toid=%d' % u).fetchone()[0]) for u in uniqueurls])
return self.normalizescores(inboundcount)
def linktextscore(self,rows,wordids):
linkscores=dict([(row[0],0) for row in rows])
for wordid in wordids:
cur=self.con.execute('select link.fromid,link.toid from linkwords,link where wordid=%d and linkwords.linkid=link.rowid' % wordid)
for (fromid,toid) in cur:
if toid in linkscores:
pr=self.con.execute('select score from pagerank where urlid=%d' % fromid).fetchone()[0]
linkscores[toid]+=pr
maxscore=max(linkscores.values())
normalizedscores=dict([(u,float(l)/maxscore) for (u,l) in linkscores.items()])
return normalizedscores
def pagerankscore(self,rows):
pageranks=dict([(row[0],self.con.execute('select score from pagerank where urlid=%d' % row[0]).fetchone()[0]) for row in rows])
maxrank=max(pageranks.values())
normalizedscores=dict([(u,float(l)/maxrank) for (u,l) in pageranks.items()])
return normalizedscores
def nnscore(self,rows,wordids):
# Get unique URL IDs as an ordered list
urlids=[urlid for urlid in dict([(row[0],1) for row in rows])]
nnres=mynet.getresult(wordids,urlids)
scores=dict([(urlids[i],nnres[i]) for i in range(len(urlids))])
return self.normalizescores(scores)
答案 0 :(得分：1)
那本书已有八年了，并且是指Python 2.4版。你错过了一个安装pysqlite2模块的步骤，但对于2.5以上版本的Python你不需要它：只需改为import sqlite3 as sqlite。