【下载文档:  python读写csv文件的方法.txt 】

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python读写csv文件的方法
1.爬取豆瓣top250书籍
import requests
import json
import csv
from bs4 import BeautifulSoup
books = []
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 next
next = 'http://book.douban.com/top250?start=0&filter='
count = 0
while 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)
结果
2.把评分为9.0的书籍保存到book_out.csv文件中
'''
1.爬取豆瓣评分排行前250本书,保存为top250.csv
2.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)
总结
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