Re: [gpsd-users] location lookup

[Ed W]

On 20/03/2012 20:01, Yan Seiner wrote:
> On Tue, March 20, 2012 12:46 pm, Gary E. Miller wrote:
> > Yo Yan!
> > Just download the flat file from the link I gave you.
> >
> > http://geonames.usgs.gov/domestic/download_data.htm
> >
> > It has lat/lons and place names.  Just search the file for the nearest
> > lat/lon and take the associated place name.  Place names are tagged by
> > type (city, mountain, etc.) so you can limit your search to just cities.
> Any suggestions on how to do the search?  "nearest" is kind of hard to
> figure out without doing a radius calc....  I'm not sure how to set up the
> database and index it so as to minimize the computational effort in
> finding the nearest point.
>
> (Storage is not a problem - I have a hard drive attached. cpu and ram are
> limited.  I have a 260 MHz CPU and 32 MB of ram.)

I've not used it, but for sqlite see:
    http://www.gaia-gis.it/gaia-sins/

The google keywords are probably "spatial" and your favourite database

Note that the main shortcut is that whilst exact (straight line) 
distance requires a circular search, you can of course bound that by the 
square which contains the circle - all databases can optimise straight 
lookups on x<lat<y and a<lon<b, so you can get pretty close quite 
easily.  Quite possibly close enough for your purposes...

Good luck

Ed W