## NAME

v.select

## DESCRIPTION

v.select allows the user to select features from a vector map by features from another one.

Supported operators (without GEOS):

- `overlap` - features partially or completely overlap Supported operators (with GEOS):
- `equals` - features are spatially equals
- `disjoint` - features do not spatially intersect
- `intersects` - features spatially intersect
- `touches` - features spatially touches
- `crosses` - features spatially crosses
- `within` - feature A is completely inside feature B
- `contains` - feature B is completely inside feature A
- `overlaps` - features spatially overlap
- `relate` - feature A is spatially related to feature B

## NOTES

Only features with category numbers will be considered. If required the v.category module can be used to add them. Typically boundaries do not need to be given a category number, as an area's attributes are inherited from the centroid. Typically points, lines, and centroids will always want to have a cat number.

E.g. take a road which separates two farms. It is ambiguous as to which farm an attribute that is attached to the road belongs to. The boundary only needs a cat number if it will hold its own attributes, such as road name or pavement form. A centroid in each paddock holds the information with respect to ownership, area, etc.

## EXAMPLES

Extract forest fire points from larger fire vector map:

    v.select ainput=fire binput=forest output=forest_fire operator=overlap

Extract Italian rivers from VMAP0 watercourses map:

    v.select ainput=watrcrsl_eurnasia_wgs84 binput=italy_area \
             output=watrcrsl_italy operator=overlap

## TODO

Processing areas with GEOS is currently incredibly slow. Significant speed-up is required.

## SEE ALSO

v.category, v.overlay

GRASS SQL interface

## AUTHORS

Radim Blazek
Updated by Martin Landa, CTU in Prague, Czech Republic (GEOS support)

Last changed: $Date: 2011-11-08 12:29:50 +0100 (Tue, 08 Nov 2011) $

Main index - vector index - Full index

© 2003-2011 GRASS Development Team