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v.select(1)		    GRASS GIS User's Manual		   v.select(1)

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	  [re-
       late=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=nameA [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 ac-
	   cess	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=nameA [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 ac-
	   cess	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=nameA [required]
	   Name	for output vector map

       operator=stringA	[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

DESCRIPTION
       v.select	 allows	 the user to select features from a vector map by fea-
       tures from another one.

       Supported operators (without GEOS; using	GRASS' own algorithm):

	   o   overlap - features partially or completely overlap (GEOS	equiv-
	       alent: intersects)
       Supported  operators  (internally  using	 GEOS  - Geometry Engine, Open
       Source):

	   o   equals -	features are spatially equals

	   o   disjoint	- features do not spatially intersect

	   o   intersects - features spatially intersect (equivalent to	native
	       'overlap')

	   o   touches - features spatially touches

	   o   crosses - features spatially crosses

	   o   within -	feature	A is completely	inside feature B

	   o   contains	- feature B is completely inside feature A

	   o   overlaps	- features spatially overlap

	   o   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	inher-
       ited from the centroid. Typically points, lines,	and centroids will al-
       ways  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
       Preparation of example data (North Carolina sample dataset):
       # Create	an grid	for overlaying to ZIP code vector map
       v.mkgrid	map=boxgrid grid=10,10 position=coor \
		coordinates=583600,201500 box=5000,5000
       # set region to ZIP codes and boxgrid vector maps
       g.region	vector=zipcodes_wake,boxgrid -p	res=100	-a
       # enlarge region	a bit for "white border" around	map in monitor
       g.region	n=n+1000 s=s-1000 w=w-1000 e=e+1000 -p
       d.mon wx0

   OVERLAP: features partially or completely overlap (using GRASS)
       Select grid boxes (North	Carolina sample	dataset):
       d.vect map=zipcodes_wake	fill_color=0:128:0
       d.vect map=boxgrid fill_color=85:130:176
       v.select	ainput=boxgrid binput=zipcodes_wake output=v_select_OVERLAP operator=overlap
       d.vect map=v_select_OVERLAP
       d.vect map=zipcodes_wake	type=boundary color=255:255:50
       v.select	with OVERLAP operator: selected	grid  boxes  shown  in	yellow
       (using GRASS method)

   OVERLAPS features spatially overlap (using GEOS)
       Select grid boxes (North	Carolina sample	dataset):
       d.vect map=zipcodes_wake	fill_color=0:128:0
       d.vect map=boxgrid fill_color=85:130:176
       v.select	ainput=boxgrid binput=zipcodes_wake output=v_select_OVERLAPS operator=overlaps
       d.vect map=v_select_OVERLAPS
       d.vect map=zipcodes_wake	type=boundary color=255:255:50
       v.select	 with  OVERLAPS	 operator: selected grid boxes shown in	yellow
       (using GEOS method)

   DISJOINT: features do not spatially intersect (using	GEOS)
       Select grid boxes (North	Carolina sample	dataset):
       d.vect map=zipcodes_wake	fill_color=0:128:0
       d.vect map=boxgrid fill_color=85:130:176
       v.select	ainput=boxgrid binput=zipcodes_wake output=v_select_DISJOINT operator=disjoint
       d.vect map=v_select_DISJOINT
       d.vect map=zipcodes_wake	type=boundary color=255:255:50
       v.select	with DISJOINT operator:	selected grid boxes shown in yellow

   EQUALS: features are	spatially equals (using	GEOS)
       Select zipcode polygon (North Carolina sample dataset):
       d.vect map=zipcodes_wake	fill_color=0:128:0
       v.extract input=zipcodes_wake where=ZIPCODE_ID=35 output=zipcodeID35
       v.select	ainput=zipcodes_wake binput=zipcodeID35	output=v_select_EQUALS operator=equals
       d.vect map=v_select_EQUALS
       d.vect map=zipcodes_wake	type=boundary color=255:255:50
       v.select	with EQUALS operator: selected grid boxes shown	in yellow

   INTERSECTS: features	spatially intersect (using GEOS)
       Select zipcode polygons (North Carolina sample dataset):
       d.vect map=zipcodes_wake	fill_color=0:128:0
       d.vect map=boxgrid fill_color=85:130:176
       v.select	ainput=zipcodes_wake binput=boxgrid output=v_select_INTERSECTS operator=intersects
       d.vect map=v_select_INTERSECTS
       d.vect map=boxgrid type=boundary	color=255:255:50
       v.select	with INTERSECTS	operator: selected grid	boxes shown in yellow

   TOUCHES: features spatially touches (using GEOS)
       Select polygons (North Carolina sample dataset):
       d.vect map=zipcodes_wake	fill_color=0:128:0
       d.vect map=zipcodeID35 fill_color=85:130:176
       v.select	ainput=zipcodes_wake binput=zipcodeID35	output=v_select_TOUCHES	operator=touches
       d.vect map=v_select_TOUCHES
       d.vect map=zipcodes_wake	type=boundary color=255:255:50
       v.select	with TOUCHES  operator:	 selected  polygons  shown  in	yellow
       (blue: input polygon)

   CROSSES: features spatially crosses (using GEOS)
       Select zipcode polygons by lines	(North Carolina	sample dataset):
       d.vect map=zipcodes_wake	fill_color=0:128:0
       d.vect map=busroute1 color=200:27:27 width=3
       v.select	ainput=zipcodes_wake binput=busroute1 output=v_select_CROSSES operator=crosses
       d.vect map=v_select_CROSSES
       d.vect map=zipcodes_wake	type=boundary color=255:255:50
       d.vect map=busroute1 color=200:27:27 width=3
       v.select	with CROSSES operator: selected	polygons shown in yellow (red:
       input lines)

   WITHIN feature A is completely inside feature B (using GEOS)
       Select zipcode polygons (North Carolina sample dataset):
       d.vect map=zipcodes_wake	fill_color=0:128:0
       d.vect map=boundary_county fill_color=85:130:176
       v.select	ainput=zipcodes_wake binput=boundary_county output=v_select_WITHIN operator=within
       d.vect map=v_select_WITHIN
       v.select	with WITHIN operator: selected polygons	shown in yellow	(blue:
       input polygons)

   CONTAINS feature B is completely inside feature A (using GEOS)
       Select zipcode polygon (North Carolina sample dataset):

   CONTAINS with polygons
       d.vect map=zipcodes_wake	fill_color=0:128:0
       d.vect map=zipcodeID35 fill_color=85:130:176
       v.select	ainput=zipcodes_wake binput=zipcodeID35	\
		output=v_select_CONTAINS_pol operator=contains
       d.vect map=v_select_CONTAINS
       v.select	 with  CONTAINS	 operator:  selected  polygon  shown in	yellow
       (blue: input polygon, not visible)

   CONTAINS with points
       d.vect map=zipcodes_wake	fill_color=0:128:0
       d.vect map=hospitals fill_color=195:31:31 icon=basic/cross3 size=10
       v.select	ainput=zipcodes_wake binput=hospitals \
		output=v_select_CONTAINS_pnts operator=contains
       d.vect map=v_select_CONTAINS_pnts
       d.vect map=hospitals fill_color=195:31:31 icon=basic/cross3 size=10
       v.select	with CONTAINS operator:	 selected  polygons  shown  in	yellow
       (red: input points)

   RELATE feature A is spatially related to feature B (using GEOS)
       This  operator additionally requires the	relate parameter (in other GIS
       called 'ST_Relate').  This operator allows calculating  the  Dimension-
       ally  Extended  nine-Intersection Model (DE-9IM).  In the following one
       example:	Select polygon with 'TOUCHES' operator (North Carolina	sample
       dataset):
       d.vect map=zipcodes_wake	fill_color=0:128:0
       d.vect map=zipcodeID35 fill_color=85:130:176
       v.select	ainput=zipcodeID35 binput=zipcodes_wake	\
		output=v_select_TOUCHES_relate operator=relate relate='T********'
       d.vect map=v_select_TOUCHES
       The result of relate='T********'	is the same as seen above in the exam-
       ple 'TOUCHES'.  See the DE-9IM page for	related	 operators  and	 their
       definition.

   Extraction of points	falling	into a polygon
       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

   Extraction of lines overlapping with	a polygon
       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

   Extraction of areas overlapping with	a line
       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

SEE ALSO
	v.category, v.clip, v.overlay, v.extract

       GRASS SQL interface
       GEOS - Geometry Engine, Open Source

AUTHORS
       Radim Blazek
       GEOS support by Martin Landa, Czech  Technical  University  in  Prague,
       Czech Republic
       ZIP code	examples by Carol X. Garzon-Lopez, Trento, Italy

SOURCE CODE
       Available at: v.select source code (history)

       Main  index  | Vector index | Topics index | Keywords index | Graphical
       index | Full index

       A(C) 2003-2020 GRASS Development	Team, GRASS GIS	7.8.3 Reference	Manual

GRASS 7.8.3							   v.select(1)

NAME | KEYWORDS | SYNOPSIS | DESCRIPTION | NOTES | EXAMPLES | SEE ALSO | AUTHORS | SOURCE CODE

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