[GRASS-user] Point count with large vectors

[Moritz Lennert]

On 09/05/09 00:51, Richard Chirgwin wrote:
> Hi all,
> 
> I'm not sure if this has been solved before.
> 
> I have two large points files (>20,000 sites), and I want to find the number of
> points in A falling within a given distance of the points in B. So the desired
> output would be:
> 
> Cat	Point count from B
> 1	10
> 2	3
> 3	12
> ...etc
> 
> I can use a buffer from Map A and run v.distance, but it takes an extremely long
> time, so suggestions would be welcome!

Don't know if this would be much faster (what takes a long time in your 
approach ?), but you could use only v.distance to create a distance 
matrix (-a), and setting the threshold dmax to your distance.
Then a simple aggregate query on the reulting table should give you what 
you need.

Moritz