strategies for finding duplicate mailing addresses

Question

I'm trying to come up with a method of finding duplicate addresses, based on a similarity score. Consider these duplicate addresses:

addr_1 = '# 3 FAIRMONT LINK SOUTH'
addr_2 = '3 FAIRMONT LINK S'

addr_3 = '5703 - 48TH AVE'
adrr_4 = '5703- 48 AVENUE'

I'm planning on applying some string transformation to make long words abbreviated, like NORTH -> N, remove all spaces, commas and dashes and pound symbols. Now, having this output, how can I compare addr_3 with the rest of addresses and detect similar? What percentage of similarity would be safe? Could you provide a simple python code for this?

addr_1 = '3FAIRMONTLINKS'
addr_2 = '3FAIRMONTLINKS'

addr_3 = '570348THAV'
adrr_4 = '570348AV'

Thankful,

Eduardo

Answer 1

First, simplify the address string by collapsing all whitespace to a single space between each word, and forcing everything to lower case (or upper case if you prefer):

adr = " ".join(adr.tolower().split())

Then, I would strip out things like "st" in "41st Street" or "nd" in "42nd Street":

adr = re.sub("1st(\b|$)", r'1', adr)
adr = re.sub("([2-9])\s?nd(\b|$)", r'\1', adr)

Note that the second sub() will work with a space between the "2" and the "nd", but I didn't set the first one to do that; because I'm not sure how you can tell the difference between "41 St Ave" and "41 St" (that second one is "41 Street" abbreviated).

Be sure to read all the help for the re module; it's powerful but cryptic.

Then, I would split what you have left into a list of words, and apply the Soundex algorithm to list items that don't look like numbers:

http://en.wikipedia.org/wiki/Soundex

http://wwwhomes.uni-bielefeld.de/gibbon/Forms/Python/SEARCH/soundex.html

adrlist = [word if word.isdigit() else soundex(word) for word in adr.split()]

Then you can work with the list or join it back to a string as you think best.

The whole idea of the Soundex thing is to handle misspelled addresses. That may not be what you want, in which case just ignore this Soundex idea.

Good luck.