Python - 之前的列表元素在while循環期間被新元素覆蓋

Question

你好，我是Python新手，想弄清楚爲什麼我的列表每當新的頁面在while循環中被加載和刮取時都會覆蓋前面的元素。先謝謝你。

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

因爲您在每次迭代循環中將urls重置爲空列表。你應該把它移到循環之前。

（注意，整個事情會更好表示爲一個循環。）

Answer 2

您需要循環之前初始化URL列表。如果你在循環中初始化它，它會將它設置爲每次都沒有。

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