1v.select(1) Grass 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
18 [relate=string] [--overwrite] [--help] [--verbose] [--quiet]
19 [--ui]
20 Flags:
22 -t
23 Do not create attribute table
24 -c
26 Do not skip features without category
27 -r
29 Reverse selection
30 --overwrite
32 Allow output files to overwrite existing files
33 --help
35 Print usage summary
36 --verbose
38 Verbose module output
39 --quiet
41 Quiet module output
42 --ui
44 Force launching GUI dialog
45 Parameters:
47 ainput=name [required]
48 Name of input vector map
49 Input vector map from which to select features (A)
50 alayer=string
52 Layer number (vector map A)
53 Vector features can have category values in different layers. This
54 number determines which layer to use. When used with direct OGR
55 access this is the layer name.
56 Default: 1
57 atype=string[,string,...]
59 Feature type (vector map A)
60 Input feature type
61 Options: point, line, boundary, centroid, area
62 Default: point,line,area
63 binput=name [required]
65 Name of input vector map
66 Query vector map (B)
67 blayer=string
69 Layer number (vector map B)
70 Vector features can have category values in different layers. This
71 number determines which layer to use. When used with direct OGR
72 access this is the layer name.
73 Default: 1
74 btype=string[,string,...]
76 Feature type (vector map B)
77 Input feature type
78 Options: point, line, boundary, centroid, area
79 Default: point,line,area
80 output=name [required]
82 Name for output vector map
83 operator=string [required]
85 Operator defines required relation between features
86 A feature is written to output if the result of operation ’ainput
87 operator binput’ is true. An input feature is considered to be
88 true, if category of given layer is defined.
89 Options: overlap, equals, disjoint, intersects, touches, crosses,
90 within, contains, overlaps, relate
91 Default: overlap
92 overlap: features partially or completely overlap
93 equals: features are spatially equals (using GEOS)
94 disjoint: features do not spatially intersect (using GEOS)
95 intersects: features spatially intersect (using GEOS)
96 touches: features spatially touches (using GEOS)
97 crosses: features spatially crosses (using GEOS)
98 within: feature A is completely inside feature B (using GEOS)
99 contains: feature B is completely inside feature A (using GEOS)
100 overlaps: features spatially overlap (using GEOS)
101 relate: feature A is spatially related to feature B (using GEOS,
102 requires ’relate’ option)
103 relate=string
105 Intersection Matrix Pattern used for ’relate’ operator
106
108 v.select allows the user to select features from a vector map by fea‐
109 tures from another one.
110 Supported operators (without GEOS; using GRASS’ own algorithm):
112 · overlap - features partially or completely overlap (GEOS equiv‐
114 alent: intersects)
115 Supported operators (internally using GEOS - Geometry Engine, Open
116 Source):
117 · equals - features are spatially equals
119 · disjoint - features do not spatially intersect
121 · intersects - features spatially intersect (equivalent to native
123 ’overlap’)
124 · touches - features spatially touches
126 · crosses - features spatially crosses
128 · within - feature A is completely inside feature B
130 · contains - feature B is completely inside feature A
132 · overlaps - features spatially overlap
134 · relate - feature A is spatially related to feature B
136
138 Only features with category numbers will be considered. If required the
139 v.category module can be used to add them. Typically boundaries do not
140 need to be given a category number, as an area’s attributes are inher‐
141 ited from the centroid. Typically points, lines, and centroids will
142 always want to have a cat number. E.g. take a road which separates two
143 farms. It is ambiguous as to which farm an attribute that is attached
144 to the road belongs to. The boundary only needs a cat number if it will
145 hold its own attributes, such as road name or pavement form. A centroid
146 in each paddock holds the information with respect to ownership, area,
147 etc.
148
150 Preparation of example data (North Carolina sample dataset):
151 # Create an grid for overlaying to ZIP code vector map
152 v.mkgrid map=boxgrid grid=10,10 position=coor \
153 coordinates=583600,201500 box=5000,5000
154 # set region to ZIP codes and boxgrid vector maps
155 g.region vector=zipcodes_wake,boxgrid -p res=100 -a
156 # enlarge region a bit for "white border" around map in monitor
157 g.region n=n+1000 s=s-1000 w=w-1000 e=e+1000 -p
158 d.mon wx0
159 OVERLAP: features partially or completely overlap (using GRASS)
161 Select grid boxes (North Carolina sample dataset):
162 d.vect map=zipcodes_wake fill_color=0:128:0
163 d.vect map=boxgrid fill_color=85:130:176
164 v.select ainput=boxgrid binput=zipcodes_wake output=v_select_OVERLAP operator=overlap
165 d.vect map=v_select_OVERLAP
166 d.vect map=zipcodes_wake type=boundary color=50:50:50
167 v.select with OVERLAP operator: selected grid boxes shown in grey
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=50:50:50
176 v.select with OVERLAPS operator: selected grid boxes shown in grey
177 DISJOINT: features do not spatially intersect (using GEOS)
179 Select grid boxes (North Carolina sample dataset):
180 d.vect map=zipcodes_wake fill_color=0:128:0
181 d.vect map=boxgrid fill_color=85:130:176
182 v.select ainput=boxgrid binput=zipcodes_wake output=v_select_DISJOINT operator=disjoint
183 d.vect map=v_select_DISJOINT
184 d.vect map=zipcodes_wake type=boundary color=50:50:50
185 v.select with DISJOINT operator: selected grid boxes shown in grey
186 EQUALS: features are spatially equals (using GEOS)
188 Select zipcode polygon (North Carolina sample dataset):
189 d.vect map=zipcodes_wake fill_color=0:128:0
190 v.extract input=zipcodes_wake where=ZIPCODE_ID=35 output=zipcodeID35
191 v.select ainput=zipcodes_wake binput=zipcodeID35 output=v_select_EQUALS operator=equals
192 d.vect map=v_select_EQUALS
193 d.vect map=zipcodes_wake type=boundary color=50:50:50
194 v.select with EQUALS operator: selected grid boxes shown in grey
195 INTERSECTS: features spatially intersect (using GEOS)
197 Select zipcode polygons (North Carolina sample dataset):
198 d.vect map=zipcodes_wake fill_color=0:128:0
199 d.vect map=boxgrid fill_color=85:130:176
200 v.select ainput=zipcodes_wake binput=boxgrid output=v_select_INTERSECTS operator=intersects
201 d.vect map=v_select_INTERSECTS
202 d.vect map=boxgrid type=boundary color=50:50:50
203 v.select with INTERSECTS operator: selected grid boxes shown in grey
204 TOUCHES: features spatially touches (using GEOS)
206 Select polygons (North Carolina sample dataset):
207 d.vect map=zipcodes_wake fill_color=0:128:0
208 d.vect map=zipcodeID35 fill_color=85:130:176
209 v.select ainput=zipcodes_wake binput=zipcodeID35 output=v_select_TOUCHES operator=touches
210 d.vect map=v_select_TOUCHES
211 d.vect map=zipcodes_wake type=boundary color=50:50:50
212 v.select with TOUCHES operator: selected polygons shown in grey (blue:
213 input polygon)
214 CROSSES: features spatially crosses (using GEOS)
216 Select zipcode polygons by lines (North Carolina sample dataset):
217 d.vect map=zipcodes_wake fill_color=0:128:0
218 d.vect map=busroute1 color=200:27:27 width=3
219 v.select ainput=zipcodes_wake binput=busroute1 output=v_select_CROSSES operator=crosses
220 d.vect map=v_select_CROSSES
221 d.vect map=zipcodes_wake type=boundary color=50:50:50
222 d.vect map=busroute1 color=200:27:27 width=3
223 v.select with CROSSES operator: selected polygons shown in grey (red:
224 input lines)
225 WITHIN feature A is completely inside feature B (using GEOS)
227 Select zipcode polygons (North Carolina sample dataset):
228 d.vect map=zipcodes_wake fill_color=0:128:0
229 d.vect map=boundary_county fill_color=85:130:176
230 v.select ainput=zipcodes_wake binput=boundary_county output=v_select_WITHIN operator=within
231 d.vect map=v_select_WITHIN
232 v.select with WITHIN operator: selected polygons shown in grey (blue:
233 input polygons)
234 CONTAINS feature B is completely inside feature A (using GEOS)
236 Select zipcode polygon (North Carolina sample dataset):
237 CONTAINS with polygons
239 d.vect map=zipcodes_wake fill_color=0:128:0
240 d.vect map=zipcodeID35 fill_color=85:130:176
241 v.select ainput=zipcodes_wake binput=zipcodeID35 \
242 output=v_select_CONTAINS_pol operator=contains
243 d.vect map=v_select_CONTAINS
244 v.select with CONTAINS operator: selected polygon shown in grey (blue:
245 input polygon, not visible)
246 CONTAINS with points
248 d.vect map=zipcodes_wake fill_color=0:128:0
249 d.vect map=hospitals fill_color=195:31:31 icon=basic/cross3 size=10
250 v.select ainput=zipcodes_wake binput=hospitals \
251 output=v_select_CONTAINS_pnts operator=contains
252 d.vect map=v_select_CONTAINS_pnts
253 d.vect map=hospitals fill_color=195:31:31 icon=basic/cross3 size=10
254 v.select with CONTAINS operator: selected polygons shown in grey (red:
255 input points)
256 RELATE feature A is spatially related to feature B (using GEOS)
258 This operator additionally requires the relate parameter (in other GIS
259 called ’ST_Relate’). This operator allows calculating the Dimension‐
260 ally Extended nine-Intersection Model (DE-9IM). In the following one
261 example: Select polygon with ’TOUCHES’ operator (North Carolina sample
262 dataset):
263 d.vect map=zipcodes_wake fill_color=0:128:0
264 d.vect map=zipcodeID35 fill_color=85:130:176
265 v.select ainput=zipcodeID35 binput=zipcodes_wake \
266 output=v_select_TOUCHES_relate operator=relate relate=’T********’
267 d.vect map=v_select_TOUCHES
268 The result of relate=’T********’ is the same as seen above in the exam‐
269 ple ’TOUCHES’. See the DE-9IM page for related operators and their
270 definition.
271 Extraction of points falling into a polygon
273 Extract fire stations (points) falling into urban area (polygon) -
274 North Carolina data set (point in polygon test):
275 v.select ainput=firestations binput=urbanarea output=urban_firestations \
276 operator=overlap
277 Extraction of lines overlapping with a polygon
279 Extract railroad lines from zip code map overlapping with the urban
280 area (line in polygon test):
281 v.select ainput=railroads binput=urbanarea \
282 output=railroads_in_urbanarea operator=overlap
283 Extraction of areas overlapping with a line
285 Extract those areas from zip code map which overlap with railroads
286 (polygon on line test):
287 # first add a tiny buffer around railroad lines:
288 v.buffer input=railroads output=railroads_buf20m \
289 distance=20
290 v.select ainput=zipcodes_wake binput=railroads_buf20m \
291 output=zipcodes_wake_railroads operator=overlap
292
294 v.category, v.clip, v.overlay, v.extract
295 GRASS SQL interface
297 GEOS - Geometry Engine, Open Source
298
300 Radim Blazek
301 GEOS support by Martin Landa, Czech Technical University in Prague,
302 Czech Republic
303 ZIP code examples by Carol X. Garzon-Lopez, Trento, Italy
304 Last changed: $Date: 2018-03-19 22:57:45 +0100 (Mon, 19 Mar 2018) $
306
308 Available at: v.select source code (history)
309 Main index | Vector index | Topics index | Keywords index | Graphical
311 index | Full index
312 © 2003-2019 GRASS Development Team, GRASS GIS 7.4.4 Reference Manual
314GRASS 7.4.4 v.select(1)