Finding all the addresses within a radius is going to be near impossible unless you have a database containing every possible address (or at least the ones you're interested in finding) along with their geocodes. Same goes with zip codes. There are several methods that can be used to determine zip codes within a radius:
1. Using centroid to centroid matching. Centroid matching takes the center of the zip code and uses the Haversine (or similar) formula to compute point to point distance. It's fairly straight forward once you have a database of zip code centroids. The downside of this method is centroid is often not very representative of a zip code, unless you're using very large distances, like 100+ miles. 2. Using edge to edge matching. This method requires a database of zip code polygons and uses an algorithm to calculate the edges that are within the radius of the edge of a particular zip code. While more accurate, this method is also more complex. Using a spatially enabled database will make this a snap though. 3. Wholly enclosed polygon matching. This method also uses a polygon database and requires all candidates to be wholly contained within the radius. Again, complex but depending on what you're trying to do, may be the best. The API itself has no facility to do these type of calculates as there is no data available to do them. You'll have to supply the data and do the calculations yourself. Hope this helps. -John Coryat http://maps.huge.info http://www.usnaviguide.com --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google Maps API" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/Google-Maps-API?hl=en -~----------~----~----~----~------~----~------~--~---
