python regular expression for domain names

问题

I am trying use the following regular expression to extract domain name from a text, but it just produce nothing, what's wrong with it? I don't know if this is suitable to ask this "fix code" question, maybe I should read more. I just want to save some time. Thanks

pat_url = re.compile(r'''

            (?:https?://)*

            (?:[\w]+[\-\w]+[.])*

            (?P<domain>[\w\-]*[\w.](com|net)([.](cn|jp|us))*[/]*)

            ''')

print re.findall(pat_url,"http://www.google.com/abcde")

I want the output to be google.com

回答1:

Don't use regex for this. Use the urlparse standard library instead. It's far more straightforward and easier to read/maintain.

http://docs.python.org/library/urlparse.html

回答2:

The first is that you're missing the re.VERBOSE flag in the call to re.compile(). The second is that you should use the methods on the returned object. The third is that you're using a regular expression where an appropriate parser already exists in the stdlib.

回答3:

This is the only correct way to parse an url with a regex:

It's in C++ but you'll find trivial to convert to python by removing additional \. And with an enum for the captures.

Also see RFC3986 as original source for the regexp.

static const char* const url_regex[] = {
    /* RE_URL */
    "^(([^:/?#]+):)?(//([^/?#]*)|///)?([^?#]*)(\\?[^#]*)?(#.*)?",
};

enum {
    URL = 0,
    SCHEME_CLN = 1,
    SCHEME  = 2,
    DSLASH_AUTH = 3,
    AUTHORITY = 4,
    PATH    = 5,
    QUERY   = 6,
    FRAGMENT = 7
};

回答4:

I don't believe that this is actually about "regression", is it? It's about regular expressions, which is a totally different thing. Perhaps someone should fix the tagging.

回答5:

([a-z0-9][-a-z0-9]*[a-z0-9]|[a-z0-9])\.(COMMUNITY|DIRECTORY|EDUCATION|EQUIPMENT|INSTITUTE|MARKETING|SOLUTIONS|XN--J1AMH|XN--L1ACC|BARGAINS|BOUTIQUE|BUILDERS|CATERING|CLEANING|CLOTHING|COMPUTER|DEMOCRAT|DIAMONDS|GRAPHICS|HOLDINGS|LIGHTING|PARTNERS|PLUMBING|TRAINING|VENTURES|XN--P1AI|ACADEMY|CAREERS|COMPANY|CRUISES|DOMAINS|EXPOSED|FLIGHTS|FLORIST|GALLERY|GUITARS|HOLIDAY|KITCHEN|RECIPES|RENTALS|REVIEWS|SHIKSHA|SINGLES|SUPPORT|SYSTEMS|AGENCY|BERLIN|CAMERA|CENTER|COFFEE|CONDOS|DATING|ESTATE|EVENTS|EXPERT|FUTBOL|KAUFEN|LUXURY|MAISON|MONASH|MUSEUM|NAGOYA|PHOTOS|REPAIR|REPORT|SOCIAL|TATTOO|TIENDA|TRAVEL|VIAJES|VILLAS|VISION|VOTING|VOYAGE|BUILD|CARDS|CHEAP|CODES|DANCE|EMAIL|GLASS|HOUSE|NINJA|PARTS|PHOTO|SHOES|SOLAR|TODAY|TOKYO|TOOLS|WATCH|WORKS|AERO|ARPA|ASIA|BIKE|BLUE|BUZZ|CAMP|CLUB|COOL|COOP|FARM|GIFT|GURU|INFO|JOBS|KIWI|LAND|LIMO|LINK|MENU|MOBI|MODA|NAME|PICS|PINK|POST|QPON|RICH|RUHR|SEXY|TIPS|WANG|WIEN|ZONE|BIZ|CAB|CAT|CEO|COM|EDU|GOV|INT|KIM|MIL|NET|ONL|ORG|PRO|RED|TEL|UNO|WED|XXX|AC|AD|AE|AF|AG|AI|AL|AM|AN|AO|AQ|AR|AS|AT|AU|AW|AX|AZ|BA|BB|BD|BE|BF|BG|BH|BI|BJ|BM|BN|BO|BR|BS|BT|BV|BW|BY|BZ|CA|CC|CD|CF|CG|CH|CI|CK|CL|CM|CN|CO|CR|CU|CV|CW|CX|CY|CZ|DE|DJ|DK|DM|DO|DZ|EC|EE|EG|ER|ES|ET|EU|FI|FJ|FK|FM|FO|FR|GA|GB|GD|GE|GF|GG|GH|GI|GL|GM|GN|GP|GQ|GR|GS|GT|GU|GW|GY|HK|HM|HN|HR|HT|HU|ID|IE|IL|IM|IN|IO|IQ|IR|IS|IT|JE|JM|JO|JP|KE|KG|KH|KI|KM|KN|KP|KR|KW|KY|KZ|LA|LB|LC|LI|LK|LR|LS|LT|LU|LV|LY|MA|MC|MD|ME|MG|MH|MK|ML|MM|MN|MO|MP|MQ|MR|MS|MT|MU|MV|MW|MX|MY|MZ|NA|NC|NE|NF|NG|NI|NL|NO|NP|NR|NU|NZ|OM|PA|PE|PF|PG|PH|PK|PL|PM|PN|PR|PS|PT|PW|PY|QA|RE|RO|RS|RU|RW|SA|SB|SC|SD|SE|SG|SH|SI|SJ|SK|SL|SM|SN|SO|SR|ST|SU|SV|SX|SY|SZ|TC|TD|TF|TG|TH|TJ|TK|TL|TM|TN|TO|TP|TR|TT|TV|TW|TZ|UA|UG|UK|US|UY|UZ|VA|VC|VE|VG|VI|VN|VU|WF|WS|YE|YT|ZA|ZM|ZW)(?![-0-9a-z])(?!\.[a-z0-9])

This Regex uses all current valid TLDs found http://data.iana.org/TLD/tlds-alpha-by-domain.txt it will take a list of text and only return the domain.tld

Eg. Feed it