NAME
v.select - Selects features from vector map (A) by features from other vector map (B).
KEYWORDS
vector,
geometry,
spatial query
SYNOPSIS
v.select
v.select --help
v.select [-tcr] ainput=name [alayer=string] [atype=string[,string,...]] binput=name [blayer=string] [btype=string[,string,...]] output=name operator=string [relate=string] [--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
- -t
- Do not create attribute table
- -c
- Do not skip features without category
- -r
- Reverse selection
- --overwrite
- Allow output files to overwrite existing files
- --help
- Print usage summary
- --verbose
- Verbose module output
- --quiet
- Quiet module output
- --ui
- Force launching GUI dialog
Parameters:
- ainput=name [required]
- Name of input vector map
- Input vector map from which to select features (A)
- alayer=string
- Layer number (vector map A)
- Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
- Default: 1
- atype=string[,string,...]
- Feature type (vector map A)
- Input feature type
- Options: point, line, boundary, centroid, area
- Default: point,line,area
- binput=name [required]
- Name of input vector map
- Query vector map (B)
- blayer=string
- Layer number (vector map B)
- Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
- Default: 1
- btype=string[,string,...]
- Feature type (vector map B)
- Input feature type
- Options: point, line, boundary, centroid, area
- Default: point,line,area
- output=name [required]
- Name for output vector map
- operator=string [required]
- Operator defines required relation between features
- A feature is written to output if the result of operation 'ainput operator binput' is true. An input feature is considered to be true, if category of given layer is defined.
- Options: overlap, equals, disjoint, intersects, touches, crosses, within, contains, overlaps, relate
- Default: overlap
- overlap: features partially or completely overlap
- equals: features are spatially equals (using GEOS)
- disjoint: features do not spatially intersect (using GEOS)
- intersects: features spatially intersect (using GEOS)
- touches: features spatially touches (using GEOS)
- crosses: features spatially crosses (using GEOS)
- within: feature A is completely inside feature B (using GEOS)
- contains: feature B is completely inside feature A (using GEOS)
- overlaps: features spatially overlap (using GEOS)
- relate: feature A is spatially related to feature B (using GEOS, requires 'relate' option)
- relate=string
- Intersection Matrix Pattern used for 'relate' operator
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
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.
Extract fire stations (points) falling into urban area (polygon) - North Carolina
data set (point in polygon test):
v.select ainput=firestations binput=urbanarea output=urban_firestations \
operator=overlap
Extract railroad lines from zip code map overlapping with the urban area
(line in polygon test):
v.select ainput=railroads binput=urbanarea \
output=railroads_in_urbanarea operator=overlap
Extract those areas from zip code map which overlap with railroads
(polygon on line test):
# first add a tiny buffer around railroad lines:
v.buffer input=railroads output=railroads_buf20m \
distance=20
v.select ainput=zipcodes_wake binput=railroads_buf20m \
output=zipcodes_wake_railroads operator=overlap
Processing areas with GEOS is currently incredibly slow. Significant
speed-up is desired.
v.category,
v.overlay,
v.extract
GRASS SQL interface
Radim Blazek
GEOS support by Martin Landa, Czech Technical University in Prague, Czech Republic
Last changed: $Date: 2014-09-24 17:43:34 +0200 (Wed, 24 Sep 2014) $
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