## 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 fire stations (points) from urban area map (polygon) - North Carolina data set:

    v.select ainput=firestations binput=urbanarea output=urban_firestations \
             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, v.extract

GRASS SQL interface

## AUTHORS

Radim Blazek
GEOS support by Martin Landa, Czech Technical University in Prague, Czech Republic

Last changed: $Date$