拜托!不要在regex中解析HTML使用bs4这样的模块。但如果你坚持这样做的话:

import requests
import re

url = 'https://en.wikipedia.org/wiki/Collatz_conjecture'
text = requests.get(url).text
tags = re.findall('<[^>]*>',text)

total=[]

for i in range(len(tags)):
    total.append(re.match('<[^\s\>]+',tags[i]).group())

total=[elem+'>' for elem in total]
r= re.compile('</[^<]')

unwanted =list(filter(r.match,total))

un=['<!-->','<!--[if>','<!DOCTYPE>','<![endif]-->']
unwanted.extend(un)

final=[x for x in list(set(total)) if x not in set(unwanted)]

print('Number of Unique HTML tags : ',len(final))

下面将从所讨论的URL中得到63个URL

import requests
import re

url = "https://en.wikipedia.org/wiki/Collatz_conjecture"
text = requests.get(url).text

url_pattern = r"((http(s)?://)([\w-]+\.)+[\w-]+[.com]+([\w\-\.,@?^=%&:/~\+#]*[\w\-\@?^=%&/~\+#])?)"

# Get all matching patterns of url_pattern
# this will return a list of tuples 
# where we are only interested in the first item of the tuple
urls = re.findall(url_pattern, text)

# using list comprehension to get the first item of the tuple, 
# and the set function to filter out duplicates
unique_urls = set([x[0] for x in urls])
print(f'Number of unique HTML tags: {len(unique_urls)} found on {url}')

输出:

Number of unique HTML tags: 63 found on https://en.wikipedia.org/wiki/Collatz_conjecture