[mapserver-users] Flexible queries (to support address lookups)

[Steve Lime]

I think we'd need fuzzy match operator, probably one specific to address 
matching. This would involve adding a C function(s) to compare to addresses
strings and then tweaking the MapServer yacc grammar to recognize the
new operator. The trick would obviously to write the C function and there are
folks on the list with considerable experience with that problem.

If you HAD that operator then presumably you could write different filters
depending on your data, e.g.:

  ('user entered address' addreq '[address column]') or
  ('user entered address' addreq '[prefix] [name] [type] [suffix]')

That would be faster than trying to manipulate the current operators. You could
also do a very generic query, like a case insensitive lookup on the street name
and then operate on that result set in your application to deal with data
differences.

Steve

>>> "Emerson, Gabe" <gemerson at WelshCo.com> 09/17/08 10:16 AM >>>
Hi All,

I have an interesting mini-project which some of you might have dealt
with before, I'd be interested in any suggestions. 

I'd like to run a query (presented to users as an address search),
across multiple layers. For example, after an address is entered, the
system first searches an in-house dataset, if there are no matches it
searches a county parcel dataset, and if both fail, it tries to map the
address via a geocoding API.
 
The issue I'm running into is that each of the layers stores addresses a
little differently. The in-house set tends to be sloppy about
punctuation and things like directions ('N' vs 'North', 'St' vs 'ST.' vs
'Street',  etc).  The county is more standardized but breaks everything
up into street prefix, name, type, suffix, etc. (Minnesota Met Council,
for those of you familiar with it). In addition, users tend not to enter
addresses the same way twice, and to leave out things like the street
type and direction.

I'm wondering if there's a way to relax the query matches so that
something like "100 James" will return a match from a DBF containing
"100 South James Ave", or a set of columns like "100" "S" "James" "Ave".
Something along the lines of  The Geocoding API is flexible in this way,
so one solution I considered is to use it as an address parser and then
use  the returned X,Y data for an itemquery on each of the layers. The
problems with that are slower performance  and possible API
unavailability. 

Currently I'm using Mapserver in CGI mode with some Javascript for
frontend logic and custom tools. I developed the application this way
for various reasons, but am considering moving to PHP Mapscript for
better performance.  If something like this is possible with the CGI
approach I'd love to hear about it, but I'd also be interested in
mapscript ideas or examples. 

Thanks!

-Gabe

Gabe Emerson
Research Department
Welsh Companies
4350 Baker Road, Suite 400
Minnetonka, MN 55343-8695
952-897-7700, ext. 1306
gemerson at welshco.com