Python 正则表达式匹配字符串中的http链接方法

import re
pattern = re.compile(r'http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+') # 匹配模式

string = 'Its after 12 noon, do you know where your rooftops are? http://tinyurl.com/NYCRooftops '
url = re.findall(pattern,string)
print url

['http://tinyurl.com/NYCRooftops']