1v.select(1) GRASS GIS User's Manual v.select(1)
2
6 v.select - Selects features from vector map (A) by features from other
7 vector map (B).
8
10 vector, geometry, spatial query
11
13 v.select
14 v.select --help
15 v.select [-tcr] ainput=name [alayer=string]
16 [atype=string[,string,...]] binput=name [blayer=string]
17 [btype=string[,string,...]] output=name operator=string [re‐
18 late=string] [--overwrite] [--help] [--verbose] [--quiet] [--ui]
19 Flags:
21 -t
22 Do not create attribute table
23 -c
25 Do not skip features without category
26 -r
28 Reverse selection
29 --overwrite
31 Allow output files to overwrite existing files
32 --help
34 Print usage summary
35 --verbose
37 Verbose module output
38 --quiet
40 Quiet module output
41 --ui
43 Force launching GUI dialog
44 Parameters:
46 ainput=name [required]
47 Name of input vector map
48 Input vector map from which to select features (A)
49 alayer=string
51 Layer number (vector map A)
52 Vector features can have category values in different layers. This
53 number determines which layer to use. When used with direct OGR ac‐
54 cess this is the layer name.
55 Default: 1
56 atype=string[,string,...]
58 Feature type (vector map A)
59 Input feature type
60 Options: point, line, boundary, centroid, area
61 Default: point,line,area
62 binput=name [required]
64 Name of input vector map
65 Query vector map (B)
66 blayer=string
68 Layer number (vector map B)
69 Vector features can have category values in different layers. This
70 number determines which layer to use. When used with direct OGR ac‐
71 cess this is the layer name.
72 Default: 1
73 btype=string[,string,...]
75 Feature type (vector map B)
76 Input feature type
77 Options: point, line, boundary, centroid, area
78 Default: point,line,area
79 output=name [required]
81 Name for output vector map
82 operator=string [required]
84 Operator defines required relation between features
85 A feature is written to output if the result of operation ’ainput
86 operator binput’ is true. An input feature is considered to be
87 true, if category of given layer is defined.
88 Options: overlap, equals, disjoint, intersects, touches, crosses,
89 within, contains, overlaps, relate
90 Default: overlap
91 overlap: features partially or completely overlap
92 equals: features are spatially equals (using GEOS)
93 disjoint: features do not spatially intersect (using GEOS)
94 intersects: features spatially intersect (using GEOS)
95 touches: features spatially touches (using GEOS)
96 crosses: features spatially crosses (using GEOS)
97 within: feature A is completely inside feature B (using GEOS)
98 contains: feature B is completely inside feature A (using GEOS)
99 overlaps: features spatially overlap (using GEOS)
100 relate: feature A is spatially related to feature B (using GEOS,
101 requires ’relate’ option)
102 relate=string
104 Intersection Matrix Pattern used for ’relate’ operator
105
107 v.select allows the user to select features from a vector map by fea‐
108 tures from another one.
109 Supported operators (without GEOS; using GRASS’ own algorithm):
111 • overlap - features partially or completely overlap (GEOS equiv‐
113 alent: intersects)
114 Supported operators (internally using GEOS - Geometry Engine, Open
115 Source):
116 • equals - features are spatially equals
118 • disjoint - features do not spatially intersect
120 • intersects - features spatially intersect (equivalent to native
122 ’overlap’)
123 • touches - features spatially touches
125 • crosses - features spatially crosses
127 • within - feature A is completely inside feature B
129 • contains - feature B is completely inside feature A
131 • overlaps - features spatially overlap
133 • relate - feature A is spatially related to feature B
135
137 Only features with category numbers will be considered. If required the
138 v.category module can be used to add them. Typically boundaries do not
139 need to be given a category number, as an area’s attributes are inher‐
140 ited from the centroid. Typically points, lines, and centroids will al‐
141 ways want to have a cat number. E.g. take a road which separates two
142 farms. It is ambiguous as to which farm an attribute that is attached
143 to the road belongs to. The boundary only needs a cat number if it will
144 hold its own attributes, such as road name or pavement form. A centroid
145 in each paddock holds the information with respect to ownership, area,
146 etc.
147
149 Preparation of example data (North Carolina sample dataset):
150 # Create an grid for overlaying to ZIP code vector map
151 v.mkgrid map=boxgrid grid=10,10 position=coor \
152 coordinates=583600,201500 box=5000,5000
153 # set region to ZIP codes and boxgrid vector maps
154 g.region vector=zipcodes_wake,boxgrid -p res=100 -a
155 # enlarge region a bit for "white border" around map in monitor
156 g.region n=n+1000 s=s-1000 w=w-1000 e=e+1000 -p
157 d.mon wx0
158 OVERLAP: features partially or completely overlap (using GRASS)
160 Select grid boxes (North Carolina sample dataset):
161 d.vect map=zipcodes_wake fill_color=0:128:0
162 d.vect map=boxgrid fill_color=85:130:176
163 v.select ainput=boxgrid binput=zipcodes_wake output=v_select_OVERLAP operator=overlap
164 d.vect map=v_select_OVERLAP
165 d.vect map=zipcodes_wake type=boundary color=255:255:50
166 v.select with OVERLAP operator: selected grid boxes shown in yellow
167 (using GRASS method)
168 OVERLAPS features spatially overlap (using GEOS)
170 Select grid boxes (North Carolina sample dataset):
171 d.vect map=zipcodes_wake fill_color=0:128:0
172 d.vect map=boxgrid fill_color=85:130:176
173 v.select ainput=boxgrid binput=zipcodes_wake output=v_select_OVERLAPS operator=overlaps
174 d.vect map=v_select_OVERLAPS
175 d.vect map=zipcodes_wake type=boundary color=255:255:50
176 v.select with OVERLAPS operator: selected grid boxes shown in yellow
177 (using GEOS method)
178 DISJOINT: features do not spatially intersect (using GEOS)
180 Select grid boxes (North Carolina sample dataset):
181 d.vect map=zipcodes_wake fill_color=0:128:0
182 d.vect map=boxgrid fill_color=85:130:176
183 v.select ainput=boxgrid binput=zipcodes_wake output=v_select_DISJOINT operator=disjoint
184 d.vect map=v_select_DISJOINT
185 d.vect map=zipcodes_wake type=boundary color=255:255:50
186 v.select with DISJOINT operator: selected grid boxes shown in yellow
187 EQUALS: features are spatially equals (using GEOS)
189 Select zipcode polygon (North Carolina sample dataset):
190 d.vect map=zipcodes_wake fill_color=0:128:0
191 v.extract input=zipcodes_wake where=ZIPCODE_ID=35 output=zipcodeID35
192 v.select ainput=zipcodes_wake binput=zipcodeID35 output=v_select_EQUALS operator=equals
193 d.vect map=v_select_EQUALS
194 d.vect map=zipcodes_wake type=boundary color=255:255:50
195 v.select with EQUALS operator: selected grid boxes shown in yellow
196 INTERSECTS: features spatially intersect (using GEOS)
198 Select zipcode polygons (North Carolina sample dataset):
199 d.vect map=zipcodes_wake fill_color=0:128:0
200 d.vect map=boxgrid fill_color=85:130:176
201 v.select ainput=zipcodes_wake binput=boxgrid output=v_select_INTERSECTS operator=intersects
202 d.vect map=v_select_INTERSECTS
203 d.vect map=boxgrid type=boundary color=255:255:50
204 v.select with INTERSECTS operator: selected grid boxes shown in yellow
205 TOUCHES: features spatially touches (using GEOS)
207 Select polygons (North Carolina sample dataset):
208 d.vect map=zipcodes_wake fill_color=0:128:0
209 d.vect map=zipcodeID35 fill_color=85:130:176
210 v.select ainput=zipcodes_wake binput=zipcodeID35 output=v_select_TOUCHES operator=touches
211 d.vect map=v_select_TOUCHES
212 d.vect map=zipcodes_wake type=boundary color=255:255:50
213 v.select with TOUCHES operator: selected polygons shown in yellow
214 (blue: input polygon)
215 CROSSES: features spatially crosses (using GEOS)
217 Select zipcode polygons by lines (North Carolina sample dataset):
218 d.vect map=zipcodes_wake fill_color=0:128:0
219 d.vect map=busroute1 color=200:27:27 width=3
220 v.select ainput=zipcodes_wake binput=busroute1 output=v_select_CROSSES operator=crosses
221 d.vect map=v_select_CROSSES
222 d.vect map=zipcodes_wake type=boundary color=255:255:50
223 d.vect map=busroute1 color=200:27:27 width=3
224 v.select with CROSSES operator: selected polygons shown in yellow (red:
225 input lines)
226 WITHIN feature A is completely inside feature B (using GEOS)
228 Select zipcode polygons (North Carolina sample dataset):
229 d.vect map=zipcodes_wake fill_color=0:128:0
230 d.vect map=boundary_county fill_color=85:130:176
231 v.select ainput=zipcodes_wake binput=boundary_county output=v_select_WITHIN operator=within
232 d.vect map=v_select_WITHIN
233 v.select with WITHIN operator: selected polygons shown in yellow (blue:
234 input polygons)
235 CONTAINS feature B is completely inside feature A (using GEOS)
237 Select zipcode polygon (North Carolina sample dataset):
238 CONTAINS with polygons
240 d.vect map=zipcodes_wake fill_color=0:128:0
241 d.vect map=zipcodeID35 fill_color=85:130:176
242 v.select ainput=zipcodes_wake binput=zipcodeID35 \
243 output=v_select_CONTAINS_pol operator=contains
244 d.vect map=v_select_CONTAINS
245 v.select with CONTAINS operator: selected polygon shown in yellow
246 (blue: input polygon, not visible)
247 CONTAINS with points
249 d.vect map=zipcodes_wake fill_color=0:128:0
250 d.vect map=hospitals fill_color=195:31:31 icon=basic/cross3 size=10
251 v.select ainput=zipcodes_wake binput=hospitals \
252 output=v_select_CONTAINS_pnts operator=contains
253 d.vect map=v_select_CONTAINS_pnts
254 d.vect map=hospitals fill_color=195:31:31 icon=basic/cross3 size=10
255 v.select with CONTAINS operator: selected polygons shown in yellow
256 (red: input points)
257 RELATE feature A is spatially related to feature B (using GEOS)
259 This operator additionally requires the relate parameter (in other GIS
260 called ’ST_Relate’). This operator allows calculating the Dimension‐
261 ally Extended nine-Intersection Model (DE-9IM). In the following one
262 example: Select polygon with ’TOUCHES’ operator (North Carolina sample
263 dataset):
264 d.vect map=zipcodes_wake fill_color=0:128:0
265 d.vect map=zipcodeID35 fill_color=85:130:176
266 v.select ainput=zipcodeID35 binput=zipcodes_wake \
267 output=v_select_TOUCHES_relate operator=relate relate=’T********’
268 d.vect map=v_select_TOUCHES
269 The result of relate=’T********’ is the same as seen above in the exam‐
270 ple ’TOUCHES’. See the DE-9IM page for related operators and their
271 definition.
272 Extraction of points falling into a polygon
274 Extract fire stations (points) falling into urban area (polygon) -
275 North Carolina data set (point in polygon test):
276 v.select ainput=firestations binput=urbanarea output=urban_firestations \
277 operator=overlap
278 Extraction of lines overlapping with a polygon
280 Extract railroad lines from zip code map overlapping with the urban
281 area (line in polygon test):
282 v.select ainput=railroads binput=urbanarea \
283 output=railroads_in_urbanarea operator=overlap
284 Extraction of areas overlapping with a line
286 Extract those areas from zip code map which overlap with railroads
287 (polygon on line test):
288 # first add a tiny buffer around railroad lines:
289 v.buffer input=railroads output=railroads_buf20m \
290 distance=20
291 v.select ainput=zipcodes_wake binput=railroads_buf20m \
292 output=zipcodes_wake_railroads operator=overlap
293
295 v.category, v.clip, v.overlay, v.extract
296 GRASS SQL interface
298 GEOS - Geometry Engine, Open Source
299
301 Radim Blazek
302 GEOS support by Martin Landa, Czech Technical University in Prague,
303 Czech Republic
304 ZIP code examples by Carol X. Garzon-Lopez, Trento, Italy
305
307 Available at: v.select source code (history)
308 Accessed: Mon Jun 20 16:47:14 2022
310 Main index | Vector index | Topics index | Keywords index | Graphical
312 index | Full index
313 © 2003-2022 GRASS Development Team, GRASS GIS 8.2.0 Reference Manual
315GRASS 8.2.0 v.select(1)