Python条件判断逻辑错误：无法正确过滤YouTube链接问题

你的代码存在两处核心逻辑错误，导致无法实现预期功能：

• 遍历逻辑混乱：通过索引遍历列表时，却用random.choice(fetchurl)随机选取url，导致当前循环的索引对应url和实际判断的url完全不相关，还会重复输出随机内容
• 条件判断错误：url != fetchurl[i].startswith(...)是将字符串类型的url和startswith返回的布尔值（True/False）做比较，这个逻辑完全不成立，必然导致错误的判断结果

修正后的代码 #

直接遍历列表中的每个url，判断其是否不以YouTube前缀开头，符合条件则打印：

import random  # 原代码漏了导入random，需补上

fetchurl = ["https://www.smithsonianmag.com/science-nature/how-wolves-really-became-dogs-180970014/",
"https://www.youtube.com/watch?v=DdPMV7GO8q0",
"https://www.npr.org/2013/01/25/170267847/canine-mystery-how-dogs-became-mans-best-friend",
"https://www.youtube.com/watch?v=DdPMV7GO8q0",
"https://www.youtube.com/watch?v=nDt0HKSdRRw&t=554",
"https://www.youtube.com/watch?v=nDt0HKSdRRw&t=554",
"https://www.youtube.com/watch?v=DdPMV7GO8q0",
"https://www.bbc.com/news/science-environment-40638584",
"https://www.youtube.com/watch?v=nDt0HKSdRRw&t=79",
"https://www.bbc.com/news/science-environment-40638584",
"https://www.newscientist.com/article/2264329-humans-may-have-domesticated-dogs-by-accident-by-sharing-excess-meat/",
"https://www.mypet.com/basic-pet-care/dog-mans-best-friend.aspx#:~:text=Scientists%20speculate%20that%20friendship%20bloomed,Those%20Who%20Must%20Be%20Obeyed.",
"https://www.youtube.com/watch?v=tggdERc8E6Y&t=11",
"https://www.npr.org/2013/01/25/170267847/canine-mystery-how-dogs-became-mans-best-friend"]

# 直接遍历列表中的每个url
for url in fetchurl:
    # 判断url是否不以YouTube前缀开头
    if not url.startswith("https://www.youtube.com/"):
        print(url)
    # 不需要输出"lol"可直接删除else分支
    # else:
    #     print("lol")

可选优化：去重输出 #

如果需要过滤重复的非YouTube链接，可以先将列表转成集合去重，再遍历：

unique_urls = list(set(fetchurl))
for url in unique_urls:
    if not url.startswith("https://www.youtube.com/"):
        print(url)

内容的提问来源于stack exchange，提问作者Info Rewind