python读写csv文件的方法

import requestsimport jsonimport csvfrom bs4 import BeautifulSoupbooks = []def book_name(url): res = requests.get(url) html = res.text soup = BeautifulSoup(html, 'html.parser') items = soup.find(class_="grid-16-8 clearfix").find(class_="indent").find_all('table') for i in items:  book = []  title = i.find(class_="pl2").find('a')  book.append('《' + title.text.replace(' ', '').replace('/n', '') + '》')  star = i.find(class_="star clearfix").find(class_="rating_nums")  book.append(star.text + '分')  try:   brief = i.find(class_="quote").find(class_="inq")  except AttributeError:   book.append('”暂无简介“')  else:   book.append(brief.text)  link = i.find(class_="pl2").find('a')['href']  book.append(link)  global books  books.append(book)  print(book) try:  next = soup.find(class_="paginator").find(class_="next").find('a')['href'] # 翻到最后一页 except TypeError:  return 0 else:  return nextnext = 'https://book.douban.com/top250?start=0&filter='count = 0while next != 0: count += 1 next = book_name(next) print('-----------以上是第' + str(count) + '页的内容-----------')csv_file = open('D:/top250_books.csv', 'w', newline='', encoding='utf-8')w = csv.writer(csv_file)w.writerow(['书名', '评分', '简介', '链接'])for b in books: w.writerow(b)

'''1.爬取豆瓣评分排行前250本书,保存为top250.csv2.读取top250.csv文件，把评分为9.0以上的书籍保存到另外一个csv文件中'''import csv#打开的时候必须用encoding='utf-8'，否则报错with open('top250.csv', encoding='utf-8') as rf: reader = csv.reader(rf) #读取头部 headers = next(reader) with open('books_out.csv', 'w', encoding='utf-8') as wf:  writer = csv.writer(wf)  #把头部信息写进去  writer.writerow(headers)  for book in reader:   #获取评分   score = book[1]   #把评分大于9.0的过滤出来   if score and float(score) >= 9.0:    writer.writerow(book)