Python - 之前的列表元素在while循环期间被新元素覆盖

Question

你好，我是Python新手，想弄清楚为什么我的列表每当新的页面在while循环中被加载和刮取时都会覆盖前面的元素。先谢谢你。

def scrapeurls(): 
    domain = "https://domain234dd.com" 
    count = 0 

    while count < 10: 

     page = requests.get("{}{}".format(domain, count)) 
     soup = BeautifulSoup(page.content, 'html.parser') 
     data = soup.findAll('div', attrs={'class': 'video'}) 

     urls = [] 

     for div in data: 
      links = div.findAll('a') 
      for a in links: 
       urls.append(a['href']) 
       print(a['href']) 

     print(count) 
     count += 1 

Answer 1

因为您在每次迭代循环中将urls重置为空列表。你应该把它移到循环之前。

（注意，整个事情会更好表示为一个循环。）

Answer 2

您需要循环之前初始化URL列表。如果你在循环中初始化它，它会将它设置为每次都没有。

Answer 3

domain = "https://domain234dd.com" 
count = 0 

urls = [] 
while count < 10: 

    page = requests.get("{}{}".format(domain, count)) 
    soup = BeautifulSoup(page.content, 'html.parser') 
    data = soup.findAll('div', attrs={'class': 'video'}) 

    for div in data: 
     links = div.findAll('a') 
     for a in links: 
      urls.append(a['href']) 
      print(a['href']) 

    print(count) 
    count += 1