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
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: $Date$