正則表達式的子域，讓`wwwboys.domain.com`

Question

我需要一個正則表達式，這將使我從每個例子的結果如下，我似乎無法得到它的權利：

example.com收益率 - >什麼/空

www.example.com收益率 - >什麼/空

account.example.com收益率 - >account

mywww.example.com收益率 - >mywww

wwwboys.example.com收益率 - >wwwboys

cool-www.example.com收益率 - >cool-www

所以，這並不重要，如果他們的子域中使用的 'www'，但它不能只是 'WWW'。它也可以包含連字符。

Answer 1

mystrings=""" 
example.com 
www.example.com 
account.example.com 
mywww.example.com 
wwwboys.example.com 
cool-www.example.com 
""" 

junk=["example.com","www.example.com"] 
for url in mystrings.split("\n"): 
    if url and not url.strip() in junk: 
     print "-->",url.split(".",2)[0] 

輸出

$ ./python.py 
--> account 
--> mywww 
--> wwwboys 
--> cool-www 

Answer 2

x="""example.com yields -> nothing/empty 

www.example.com yields -> nothing/empty 

account.example.com yields -> account 

mywww.example.com yields -> mywww 

wwwboys.example.com yields -> wwwboys 

cool-www.example.com yields -> cool-www""" 

>>> re.findall("^([A-Za-z0-9-]+)\.(?<!^www\.)[A-Za-z0-9-]+\.[A-Za-z]+",x,re.MULTILINE) 
['account', 'mywww', 'wwwboys', 'cool-www'] 

Answer 3

這裏是基於ghostdog74的例子我的解決方案：

OFF_LIMITS = ('api', 'www', 'secure', 'account') 

def get_safe_subdomain_or_none(host): 
    subdomain = None 
    L = host.split('.') 
    if len(L) is 3 and not L[0] in OFF_LIMITS: # 3 ensures that you don't have a sub-sub domain, and that you don't have just `example.com` 
     subdomain = L[0] 
    return subdomain