Python爬虫实例1

Python爬虫实例1 爬取猫眼电影TOP100（http://maoyan.com/board/4)的相关内容

step1 准备工作

目标：
爬取猫眼电影TOP100的电影名称、时间、评分、图片

分析：
第一页URL：https://maoyan.com/board/4，展示了排行1-10的电影；
第二页URL：https://maoyan.com/board/4?offset=10，展示了排行10-20的电影；
…
获取TOP100，需要分开请求10次，参数offset分别为：0，10…90

step2 获取数据

1.爬取第一页的源代码

import requests


def get_one_page(url):
    headers = {
        'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.162 Safari/537.36'
    }
    response = requests.get(url=url, headers=headers)
    html = response.text
    return html

def main():
    url = "https://maoyan.com/board/4"
    html = get_one_page(url)
    print(html)

2.正则提取信息

每个电影对应一个dd节点

 
    1
    
      


      `在这里插入代码片`
    
    
      
              
        我不是药神
        
                主演：徐峥,周一围,王传君
        
上映时间：2018-07-05
    
    
9.6

爬取信息的正则表达式：

.*?board-index.*?>(d+).*?data-src="https://www.mshxw.com/skin/sinaskin/image/nopic.gif".*?name">https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?star">https://www.mshxw.com/skin/sinaskin/image/nopic.gif
.*?releasetime">https://www.mshxw.com/skin/sinaskin/image/nopic.gif
.*?integer">https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?fraction">https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?

括号内匹配了7个信息：排名、图片、名称、主演、上映时间、评分整数部分、评分小数部分

def parse_one_page(html):
    pattern = re.compile('.*?board-index.*?>(d+).*?data-src="https://www.mshxw.com/skin/sinaskin/image/nopic.gif".*?name">
                         + '.*?>https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?star">https://www.mshxw.com/skin/sinaskin/image/nopic.gif
.*?releasetime">https://www.mshxw.com/skin/sinaskin/image/nopic.gif'
                         + '.*?integer">https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?fraction">https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?', re.S)
    items = re.findall(pattern, html)
    return items

3.处理得到的数据

数据比较杂乱，我们要对数据进行处理。
我们遍历提取结果生成字典，形成结构化数据

需要使用两个函数：
（1）yield：通俗理解，yield就是 return 返回一个值，并且记住这个返回的位置，下次迭代就从这个位置后开始
（2）strip：去掉字符串两边的空格

更新代码

def parse_one_page(html):
    pattern = re.compile('.*?board-index.*?>(d+).*?data-src="https://www.mshxw.com/skin/sinaskin/image/nopic.gif".*?name">
                         + '.*?>https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?star">https://www.mshxw.com/skin/sinaskin/image/nopic.gif
.*?releasetime">https://www.mshxw.com/skin/sinaskin/image/nopic.gif'
                         + '.*?integer">https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?fraction">https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?', re.S)
    items = re.findall(pattern, html)
    for item in items:
        yield{
            'index': item[0],
            'image': item[1],
            'title': item[2],
            'actor': item[3].strip()[3:],
            'time': item[4].strip()[5:],
            'score': item[5]+item[6]
        }

4.分页爬取
给链接传入参数offset即可

def main(offset):
    url = "https://maoyan.com/board/4?offest="+str(offset)
    html = get_one_page(url)
    for item in parse_one_page(html):
        print(item)


if __name__ == '__main__':
    for i in range(10):
        main(offset=i*10)

step3 写入文件

def write_to_file(item):
    with open('result.txt', 'a', encoding='utf-8') as f:
        print(type(json.dumps(item)))
        f.write(json.dumps(item, ensure_ascii=False)+'n')

step4 运行结果

1.完整代码：

import json
import requests
from requests.exceptions import RequestException
import re
import time


def get_one_page(url):
    try:
        headers = {
            'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.162 Safari/537.36'
        }
        response = requests.get(url, headers=headers)
        if response.status_code == 200:
            return response.text
        return None
    except RequestException:
        return None


def parse_one_page(html):
    pattern = re.compile('.*?board-index.*?>(d+).*?data-src="https://www.mshxw.com/skin/sinaskin/image/nopic.gif".*?name">
                         + '.*?>https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?star">https://www.mshxw.com/skin/sinaskin/image/nopic.gif
.*?releasetime">https://www.mshxw.com/skin/sinaskin/image/nopic.gif'
                         + '.*?integer">https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?fraction">https://www.mshxw.com/skin/sinaskin/image/nopic.gif.*?', re.S)
    items = re.findall(pattern, html)
    for item in items:
        yield {
            'index': item[0],
            'image': item[1],
            'title': item[2],
            'actor': item[3].strip()[3:],
            'time': item[4].strip()[5:],
            'score': item[5] + item[6]
        }


def write_to_file(content):
    with open('result.txt', 'a', encoding='utf-8') as f:
        f.write(json.dumps(content, ensure_ascii=False) + 'n')


def main(offset):
    url = 'http://maoyan.com/board/4?offset=' + str(offset)
    html = get_one_page(url)
    for item in parse_one_page(html):
        print(item)
        write_to_file(item)


if __name__ == '__main__':
    for i in range(10):
        main(offset=i * 10)
        time.sleep(1)

2.txt文件

Python爬虫实例1

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