Python爬虫——xpath().[0]的用法

其他 2020-04-09 10:26:59 阅读次数: 0

①

1.1   name,无[0],无循环——打印出列表

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
name=selector.xpath('//ol[@class="grid_view"]/li/div/div[2]/div[1]/a/span[1]/text()')
print(name)
#  ['肖申克的救赎', '霸王别姬'..(省去21条记录)..'怦然心动','触不可及']

1.2   name,有[0],无循环———返回列表中第一个元素

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
name=selector.xpath('//ol[@class="grid_view"]/li/div/div[2]/div[1]/a/span[1]/text()')[0]
print(name)
#  肖申克的救赎

1.3   name,有.extract()或者.extract()[0],无循环——均报错

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
name=selector.xpath('//ol[@class="grid_view"]/li/div/div[2]/div[1]/a/span[1]/text()').extract()[0]
print(name)
#  .extract()      .extract()[0] 均报错

②

2.1    name，score，无[0],无循环——打印出两个列表

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
name=selector.xpath('//ol[@class="grid_view"]/li/div/div[2]/div[1]/a/span[1]/text()')
score=selector.xpath('//ol[@class="grid_view"]/li/div/div[2]/div[2]/div/span[2]/text()')
print(name,score)
#  ['肖申克的救赎', '霸王别姬'..(省去21条记录)..'怦然心动','触不可及']['9.7','9.6'..(省去21条记录).. '9.1','9.2']

2.2.1    name，score，有[0],无循环——分别返回两个列表中的第一个元素

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
name=selector.xpath('//ol[@class="grid_view"]/li/div/div[2]/div[1]/a/span[1]/text()')[0]
score=selector.xpath('//ol[@class="grid_view"]/li/div/div[2]/div[2]/div/span[2]/text()')[0]
print(name,score)
#  肖申克的救赎 9.7

2.2.2    name，score，有[1],无循环——分别返回两个列表中的第二个元素

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
name=selector.xpath('//ol[@class="grid_view"]/li/div/div[2]/div[1]/a/span[1]/text()')[1]
score=selector.xpath('//ol[@class="grid_view"]/li/div/div[2]/div[2]/div/span[2]/text()')[1]
print(name,score)
#  霸王别姬 9.6

③有循环

3.1.1    name，score，无[0],有循环——打印出每次循环的结果

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
lis=selector.xpath('//ol[@class="grid_view"]/li')
for oneSelector in lis:
    name=oneSelector.xpath("div/div[2]/div[1]/a/span[1]/text()")
    score=oneSelector.xpath("div/div[2]/div[2]/div/span[2]/text()")
    print(name,score)
    # ['肖申克的救赎'] ['9.7']  ----第一次循环后的结果
    # ['霸王别姬'] ['9.6']  ----第二次循环后的结果
    #  .....中间省去21条记录
    # ['怦然心动'] ['9.1']
    # ['触不可及'] ['9.2']

3.1.2    name，score，有[0],有循环——打印出每次循环的结果

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
lis=selector.xpath('//ol[@class="grid_view"]/li')
for oneSelector in lis:
    name=oneSelector.xpath("div/div[2]/div[1]/a/span[1]/text()")[0]
    score=oneSelector.xpath("div/div[2]/div[2]/div/span[2]/text()")[0]
    print(name,score)
    # 肖申克的救赎 9.7  ----第一次循环后的结果
    # 霸王别姬 9.6  ----第二次循环后的结果
    #  .....中间省去21条记录
    # 怦然心动 9.1
    # 触不可及 9.2

3.1.3    name，score，有[0],有循环——打印出最终结果

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
lis=selector.xpath('//ol[@class="grid_view"]/li')
for oneSelector in lis:
    name=oneSelector.xpath("div/div[2]/div[1]/a/span[1]/text()")[0]
    score=oneSelector.xpath("div/div[2]/div[2]/div/span[2]/text()")[0]
print(name,score)
# 触不可及 9.2

④

4.1.1    name，score，people无[0],有循环,存入一个元组中——打印出每次循环的结果

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
lis=selector.xpath('//ol[@class="grid_view"]/li')
allMovieList=[]
for oneSelector in lis:
        name=oneSelector.xpath("div/div[2]/div[1]/a/span[1]/text()")
        score=oneSelector.xpath("div/div[2]/div[2]/div/span[2]/text()")
        people=oneSelector.xpath("div/div[2]/div[2]/div/span[4]/text()")
        oneMovieList=[name,score,people]
        print(oneMovieList)
# [['肖申克的救赎'], ['9.7'], ['1918400人评价']] ----第一次循环后的结果
# [['霸王别姬'], ['9.6'], ['1411167人评价']] ----第二次循环后的结果
#          ..(省去20条记录)..
# [['怦然心动'], ['9.1'], ['1193590人评价']]
# [['触不可及'], ['9.2'], ['677191人评价']]

4.1.2    name，score，people有[0],有循环,存入一个元组中——打印出每次循环的结果

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
lis=selector.xpath('//ol[@class="grid_view"]/li')
allMovieList=[]
for oneSelector in lis:
        name=oneSelector.xpath("div/div[2]/div[1]/a/span[1]/text()")[0]
        score=oneSelector.xpath("div/div[2]/div[2]/div/span[2]/text()")[0]
        people=oneSelector.xpath("div/div[2]/div[2]/div/span[4]/text()")[0]
        oneMovieList=[name,score,people]
        print(oneMovieList)
# ['肖申克的救赎', '9.7', '1918400人评价']
# ['霸王别姬', '9.6', '1411167人评价']
#          ..(省去20条记录)..
# ['怦然心动', '9.1', '1193590人评价']
# ['触不可及', '9.2', '677191人评价']

4.2.2    name，score，people无[0],有循环,存入一个元组中后逐一添加到一个大的元组中——打印每次循环的结果

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
lis=selector.xpath('//ol[@class="grid_view"]/li')
allMovieList=[]
for oneSelector in lis:
        name=oneSelector.xpath("div/div[2]/div[1]/a/span[1]/text()")
        score=oneSelector.xpath("div/div[2]/div[2]/div/span[2]/text()")
        people=oneSelector.xpath("div/div[2]/div[2]/div/span[4]/text()")
        oneMovieList=[name,score,people]
        allMovieList.append(oneMovieList)
        print(allMovieList)
# [[['肖申克的救赎'], ['9.7'], ['1918400人评价']]]
# [[['肖申克的救赎'], ['9.7'], ['1918400人评价']], [['霸王别姬'], ['9.6'], ['1411167人评价']]]
# [[['肖申克的救赎'], ['9.7'], ['1918400人评价']], [['霸王别姬'], ['9.6'], ['1411167人评价']], [['阿甘正传'], ['9.5'], ['1458464人评价']]]

4.2.3    name，score，people有[0],有循环,存入一个元组中后逐一添加到一个大的元组中——打印每次循环的结果

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
lis=selector.xpath('//ol[@class="grid_view"]/li')
allMovieList=[]
for oneSelector in lis:
        name=oneSelector.xpath("div/div[2]/div[1]/a/span[1]/text()")[0]
        score=oneSelector.xpath("div/div[2]/div[2]/div/span[2]/text()")[0]
        people=oneSelector.xpath("div/div[2]/div[2]/div/span[4]/text()")[0]
        oneMovieList=[name,score,people]
        allMovieList.append(oneMovieList)
        print(allMovieList)
# [['肖申克的救赎', '9.7', '1918400人评价']]
# [['肖申克的救赎', '9.7', '1918400人评价'], ['霸王别姬', '9.6', '1411167人评价']]
# [['肖申克的救赎', '9.7', '1918400人评价'], ['霸王别姬', '9.6', '1411167人评价'], ['阿甘正传', '9.5', '1458464人评价']]

4.3.1    name，score，people无[0],有循环,存入一个元组中后逐一添加到一个大的元组中——打印最终结果

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
lis=selector.xpath('//ol[@class="grid_view"]/li')
allMovieList=[]
for oneSelector in lis:
        name=oneSelector.xpath("div/div[2]/div[1]/a/span[1]/text()")
        score=oneSelector.xpath("div/div[2]/div[2]/div/span[2]/text()")
        people=oneSelector.xpath("div/div[2]/div[2]/div/span[4]/text()")
        oneMovieList=[name,score,people]
        allMovieList.append(oneMovieList)
print(allMovieList)
# [[['肖申克的救赎'], ['9.7'], ['1918400人评价']], [['霸王别姬'], ['9.6'],...... ['1411167人评价']], [['阿甘正传'], ['9.5'], ['1458464人评价']]]

4.3.2    name，score，people有[0],有循环,存入一个元组中后逐一添加到一个大的元组中——打印最终结果

import requests
from lxml import etree

url="https://movie.douban.com/top250"
header = {"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36"}
html = requests.get(url, headers=header).text
selector=etree.HTML(html)
lis=selector.xpath('//ol[@class="grid_view"]/li')
allMovieList=[]
for oneSelector in lis:
        name=oneSelector.xpath("div/div[2]/div[1]/a/span[1]/text()")[0]
        score=oneSelector.xpath("div/div[2]/div[2]/div/span[2]/text()")[0]
        people=oneSelector.xpath("div/div[2]/div[2]/div/span[4]/text()")[0]
        oneMovieList=[name,score,people]
        allMovieList.append(oneMovieList)
print(allMovieList)
# [['肖申克的救赎', '9.7', '1918400人评价'], ['霸王别姬', '9.6', '1411167人评价'],...... ['触不可及', '9.2', '677191人评价']]

进入Debug调试：
第一次循环：
在这里插入图片描述
第二次循环：
在这里插入图片描述
第三次循环：
在这里插入图片描述
依次类推得出最总结果。

总结：

      无[0]时返回的是一个列表，有[0]时返回的是列表中的第一个元素，熟练运用Debug模式进行调试。

施施吖
发布了27 篇原创文章 · 获赞 7 · 访问量 2130
私信 关注

猜你喜欢

转载自blog.csdn.net/lucky_shi/article/details/104851748
今日推荐
火速冲上 GitHub 热榜 —— 开源编程语言、框架哪有这么可爱？
北京人形机器人创新中心发布全球首个纯电驱拟人奔跑的全尺寸人形机器人“天工”
LFOSSA 源来如此公开课 | 掌握云原生未来：CNCF 认证全面攻略与备考秘籍
国产云输入法——仅华为无云端数据上传安全问题
开源日报 | 工业开源项目OGG 1.0；姐姐，你要和我一起配置火狐吗；苹果AI遥遥落后？Fedora 40
开放签电子签章：停止新增，优化体验，前进更进（五一假期前工作）
周排行
Metasploit文件目录与入侵基本概念
跨域(CORS)请求问题[No 'Access-Control-Allow-Origin' header is present on the requested resource]常见解决方案
CodeIgniter 源码解读之 CodeIgniter.php（二）
SAS入门之（四）改变数据类型
初识元组
[数学建模]数学建模算法和模型（B站视频）（二）
Nginx 服务器源码安装配置流程
C#实现语音视频录制 【基于MCapture + MFile】
开发进度4
下载安装vue的方法网址
每日归档
更多
2024-04-28(0)
2024-04-27(56)
2024-04-26(39)
2024-04-25(22)
2024-04-24(36)
2024-04-23(26)
2024-04-22(39)
2024-04-21(0)
2024-04-20(6)
2024-04-19(5)

代码天地 © 2018 codetd.com

境外服务器   最新电视剧2022