Geocoding - grouping multiple addresses into major cities
Hunt for previous geocoding questions, and while many are helpful, I don't find them for my needs.
I need to group several addresses into nearby city centers. My only address information is city, country and state (if applicable). For example, all addresses in San Francisco and within miles must be listed as San Francisco. I need to know the number of addresses rolled in San Francisco.
I am open to suggestions on how to approach this. I don't really want to manually identify the list of major cities if possible. Is there a list I can start from?
How about using the average distance between all addresses within miles? Of course, the final "center point" will move a little as the average is calculated, but perhaps this is a rough solution. Not really sure how to do this again, please rate the input!
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Great question. I think in general you want some kind of standard way of folding cities into megalopolises, and you are quite right that you don't want to create or maintain your own list.
Yahoo! GeoPlanet provides a geographic ontology with a fairly thorough hierarchy. If you were happy with the standard administrative divisions (such as county or state) it would be easy, but I think you are looking for something more general than that. But GeoPlanet also provides zones, often in the US, including the city of the Metropolitan Statistical Area .
Once you have the name of each city, you can use GeoPlanet to find and collapse the MSA zones that the city belongs to (and GeoPlanet provides a bounding box and center for each MSA, so you can easily place it on the map). For rural towns that are not part of the US MSA Census Bureau, you may not need to group it into the nearest town (which may be far away anyway).
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