[GRASS-user] How to find whether one vector is contained by another

[Hamish]

Patton, Eric wrote:
> A lot of time I get requests to find out what vector navigation
> tracklines fall within a certain region. This is easy to do by visual
> inspection (turning on and off vectors in gis.m) when the number of
> vectors is low, but becomes too much work for large numbers (i.e.,
> 200). What is the best way to find out if one vector is contained by
> another, without writing any output? All I need is a listing of vector
> names. 


[v.select; ... ; g.remove]


Jeroen Wortel wrote:
> A nice addition to Grass would be vector selections that are kept in 
> memory instead of written to an output file. Only the pointers to the 
> geometry need to be kept in memory, no actual geometry. These 
> selection could be used in other grass commands just like normal 
> vector maps. This mechanism works for example in GenaMap (called 
> active ID's) and is very powerful for scripting purposes and saves a 
> lot of temporary files on disk. (This would mean however that vector 
> indices should be kept in the vector files instead of created every
> time)that When doing a selection inside or a proximity in GenaMap, the
> number of selected features is returned.

there is a v.external "Memory" driver from OGR, but I'm not sure what
it does exactly.

in the GDAL source:  ogr/ogrsf_frmts/mem/
 * Project:  OpenGIS Simple Features Reference Implementation
 * Purpose:  Implements OGRMemDriver class.

but nothing I could find in:

http://gdal.org/ogr/ogr_formats.html



Hamish