Thank you Gary,
Is it true that, when i use SQLite and not the Google App Engine, the
first algorithm in that GeoBOX story is good enough, because i dont
use App Engine?
SELECT *
FROM Business
WHERE Lat > (position_lat - d) AND
Lat < (position_lat + d) AND
Lon > (position_lon - d) AND
Lon < (position_lon + d);
Last thing i need to know is how to calculate the variable "d" in the
above query, if the box is -say- a 1 mile radius.
Greets,
Martijn
On 4 sep, 08:48, gjs <[email protected]> wrote:
> Hi,
>
> There is a description about a GeoBox algorithm & some python source
> code located here -
>
> http://code.google.com/appengine/articles/geosearch.html
>
> Regards
>
> On Sep 4, 6:42 am, String <[email protected]> wrote:
>
> > This is a common problem in GIS. I'd suggest doing a simple check for
> > whether each point is within a simple lat/lon box - that should be
> > fast enough with only 400 points, and should narrow down the list
> > enough to be able to check the distance on just those few.
>
> > If you're doing this a lot, put the data in SQLite with indexes on lat
> > & lon; that way you can do this initial "box" query easily &
> > efficiently.
>
> > String
>
> > Martijn van der Plaat wrote:
>
> > > Dear all,
>
> > > In my application I have a list of +400 GPS coordinates which I
> > > retrieve from addresses. The application should give me the top X
> > > nearest coordinates based on my current location.
>
> > > This application is possible (I think) with the distanceBetween
> > > function. But (I think) the application is really inefficient when i
> > > iterate through the list of 400 coordinates and check the distance
> > > within a certain time interval.
> > > Another option is (I think) the proximityAlert function? All
> > > coordinates are loaded in this function and when my current location
> > > comes in the radius of a coordinate an alert is given. But the
> > > downside of this solution (I think) is the high memory usage which
> > > implies a short battery life of the Android phone?
>
> > > Please can anybody help me to make the right decision?
>
> > > Greets,
> > > Martijn
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