Question

I am attempting to create a regular expression to parse an address into five parts: "address1", which is the street address, "address2", which is the apartment number or whatever else shows up on line 2 of an address, the city, state, and zip code.

When I run this, Python (or Django) is throwing an error which states "unexpected end of pattern" when I run re.search. Can anyone tell me how to modify this regular expression to match correctly?

I’m very much a regular expression noob. I can make out most of what this one is supposed to do, but I could never have written it myself. I got this from http://regexlib.com/REDetails.aspx?regexp_id=472.

re.compile(r"""
(?x)^(?n:
(?<address1>
    (\d{1,5}(\ 1\/[234])?(\x20[A-Z]([a-z])+)+ )
    | (P.O. Box \d{1,5}))\s{1,2}
(?<city>
    [A-Z]([a-z]) 
        + (\.?)(\x20[A-Z]([a-z])+){0, 2})\, \x20
(?<state>
    A[LKSZRAP] | C[AOT] | D[EC] | F[LM] | G[AU] | HI
    | I[ADL N] | K[SY] | LA | M[ADEHINOPST] | N[CDEHJMVY]
    | O[HKR] | P[ARW] | RI | S[CD] | T[NX] | UT | V[AIT] 
    | W[AIVY] 
    | [A-Z]([a-z])
        + (\.?)(\x20[A-Z]([a-z])+){0,2})\x20
(?<zipcode>
    (?!0{5})\d{5}(-\d {4})?)
)$"
""", re.VERBOSE)

Newlines added for readability. As a follow-up question, can this regex be separated into multiple lines like this for readability, or will it need to be all in one line to work (I could just concatenate the separate lines, I suppose)?

P.S. I know this smells like homework, but it is actually for work.

Edit: Actual code being used was requested, so here it is. I left it out because everything here is actually already up there, but perhaps it will help.

The function is part of a Django view, but that shouldn’t matter too much for our purposes.

def parseAddress(address):
  pattern = r"^(?n:(?<address1>(\d{1,5}(\ 1\/[234])?(\x20[A-Z]([a-z])+)+ )|(P\.O\.\ Box\ \d{1,5}))\s{1,2}(?i:(?<address2>(((APT|APARTMENT|BLDG|BUILDING|DEPT|DEPARTMENT|FL|FLOOR|HNGR|HANGER|LOT|PIER|RM|ROOM|S(LIP|PC|T(E|OP))|TRLR|TRAILER|UNIT)\x20\w{1,5})|(BSMT|BASEMENT|FRNT|FRONT|LBBY|LOBBY|LOWR|LOWER|OFC|OFFICE|PH|REAR|SIDE|UPPR|UPPER)\.?)\s{1,2})?)(?<city>[A-Z]([a-z])+(\.?)(\x20[A-Z]([a-z])+){0,2})\, \x20(?<state>A[LKSZRAP]|C[AOT]|D[EC]|F[LM]|G[AU]|HI|I[ADL N]|K[SY]|LA|M[ADEHINOPST]|N[CDEHJMVY]|O[HKR]|P[ARW]|RI|S[CD] |T[NX]|UT|V[AIT]|W[AIVY]|[A-Z]([a-z])+(\.?)(\x20[A-Z]([a-z])+){0,2})\x20(?<zipcode>(?!0{5})\d{5}(-\d {4})?))$"
  match = re.search(pattern, address)

I was using my home address as the input, but I tried "123 Main St., Austin, TX 12345" as input as well with the same result.

Answer 1

Some people might not consider this an answer, but bear with me for a minute.

I HIGHLY recommend AGAINST trying to parse street addresses with a regex. Street addresses are not “regular” in any sense of the word. There is infinite variation, and unless you restrict yourself to a very limited grammar, there will always be strings you cannot parse. A huge amount of time and money has been invested in solutions to parse addresses, starting with the US Post Office and the many, many providers of list cleanup services. Just Google “parsing street addresses” to get a hint of the scope of the problem. There are commercial solutions and some free solutions, but the comments on the web indicate that nobody gets it right all the time.

I also speak from experience. During the ’80s I worked for a database typesetting company, and we had to parse addresses. We never were able to develop a solution that worked perfectly, and for data we captured ourselves (we had a large keyboarding department) we developed a special notation syntax so the operators could insert delimiters at the appropriate locations to help the parsing process.

Take a look at some of the free services out there. You will save yourself a lot of hassle.