Here’s a module I wrote (in an hour. Damn, Python is wonderful) which scrapes the US Postal service web site for three-digit zip code extensions (http://pe.usps.gov/text/dmm300/L002.htm). It creates a db table and injects zip code prefix, region and state info for each record found. It uses BeautifulSoup to parse the HTML, and SqlAlchemy to do the DB operations.

If you only need to check what region and state a particular zip code belongs, this is for you. If anyone can point me to a free longitude/latitude/full zip code site, please post that info to a reply, and I’ll rewrite this module.

import urllib2
import codecs
import re
import pdb
import os
import BeautifulSoup
import sqlalchemy

class GetZips:
	def __init__(self):
		self.zip_info = []

	def getZipPrefixes(self):
		zip_page = urllib2.urlopen("http://pe.usps.gov/text/dmm300/L002.htm").read()
		self.soup = BeautifulSoup.BeautifulSoup(zip_page)
		# match zip columns
		zips = self.soup.findAll(attrs={'class':re.compile('^trBodyRow*')})
		for i in zips:
			y = i.find(attrs={'class':re.compile('^pTblBodyLL pAlignLeft*')})
			'''
			X is the symbol for an unused 3 digit zip prefix.
			'''
			if y.span and y.span.string == 'X':
				continue

			# last 3 digits
			zip_prefix_3 = y.a.next.next
			zip_prefix_3 = re.sub('[\n\r]+','',zip_prefix_3)

			# finding the first column will suffice.
			y = i.find(attrs={'class':re.compile('^pTblBodyLL pAlignRight*')})

			region_state = y.a.next.next.split()

			region = region_state[-3]
			state_abbrev = region_state[-2]

			if region_state[-1] != zip_prefix_3:
				print "There is a problem here: %s" % i

			self.zip_info.append((region,state_abbrev,zip_prefix_3))
			print "Found %s %s %s" % (region,state_abbrev,zip_prefix_3)

	def injectIntoDB(self):
		engine = sqlalchemy.create_engine('postgres://%s:%s@%s/%s' % ('postgresql','something','127.0.0.1:5432','zip_db'),strategy='threadlocal')
		'''
		The sqlalchemy explicit scope is done for clarity. Of course
		you can "from sqlalchemy import *" instead, and change the scope
		of these calls.
		'''
		metadata = sqlalchemy.MetaData()
		metadata.bind = engine
		zip_table = sqlalchemy.Table('zip_abbrevs', metadata,
			sqlalchemy.Column('zip_abbrevs_id', sqlalchemy.Integer, primary_key=True),
			sqlalchemy.Column('three_digit_abbrev', sqlalchemy.String(4)),
			sqlalchemy.Column('region', sqlalchemy.VARCHAR(50)),
			sqlalchemy.Column('state_abbrev', sqlalchemy.String(3)))

		metadata.create_all(engine)

		for (region, state, zip) in self.zip_info:
			print "Injecting %s %s %s\n" % (region, state,zip)
			zip_table.insert(values={'region':region,'state_abbrev':state,'three_digit_abbrev':zip}).execute()

if __name__ == "__main__":
	x=GetZips()
	x.getZipPrefixes()
	x.injectIntoDB()

# vim:ts=4: noet:

I am writing this code for the nonprofit called The Freelancer’s Union in NYC, which currently has a nationwide member drive: http://www.freelancersunion.org/advocacy/index.html.
I will shamelessly plug them in exchange for sharing this code with the world.

The more members they get in each US state, the better nationwide insurance plans they can offer. They offer E&O insurance for IT freelancers as well, so even if you freelance part-time, this could be for you. This organization rocks. I’ve been a member for three years, and now I proudly write code for them.

Gloria

The unmodified code

This blog entry was posted on Thursday, April 17th, 2008 at 2:31 pm and is filed under Database, Python, Thoughts. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.