[GRASS-user] shortest distance within a points layer

Moritz Lennert mlennert at club.worldonline.be
Mon Aug 11 07:57:18 EDT 2008

On 11/08/08 12:49, G. Allegri wrote:
> It means that I have to select shortest distances from the distance
> matrix from outside GRASS (because I can't use MIN, GROUP BY, and
> similar statements with db.select with DBF driver), and then update
> somehow the points attrbitutes from the previous selection... Mmm,
> it's quite a common task, there should be something more
> straightforward.

Well, if you move to sqlite (which will be the default in the future), 
the task becomes pretty straightforward...

But maybe we can look into adding a minimum threshold to v.distance 
(i.e. only record distances above a certain threshold).


> 2008/8/11 Alex Mandel <tech_dev at wildintellect.com>:
>> G. Allegri wrote:
>>> Hi lis
>>> I need to evaluate the shortest distance between the points of the same
>>> layer .
>>> v.distance fails as to_map and from_map overlap (every shortest
>>> distance is obviously 0: from point to itself). I was considering the
>>> use of network analysis tools... but I don't see a straigthforward way
>>> with them.
>>> Giovanni
>> How about v.distance -a which creates a distance matrix then you can query
>> the table for lowest value, group by point and exclude distances of 0.
>> see http://www.grass.itc.it/gdp/html_grass63/v.distance.html
>> Alex
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