1v.category(1) GRASS GIS User's Manual v.category(1)
2
6 v.category - Attaches, deletes or reports vector categories to/from/of
7 map geometry.
8
10 vector, category, layer
11
13 v.category
14 v.category --help
15 v.category [-gt] input=name [layer=string[,string,...]]
16 [type=string[,string,...]] [ids=range] [output=name] option=string
17 [cat=integer] [step=integer] [--overwrite] [--help] [--verbose]
18 [--quiet] [--ui]
19 Flags:
21 -g
22 Shell script style, currently only for report
23 Format: layer type count min max
24 -t
26 Do not copy attribute table(s)
27 --overwrite
29 Allow output files to overwrite existing files
30 --help
32 Print usage summary
33 --verbose
35 Verbose module output
36 --quiet
38 Quiet module output
39 --ui
41 Force launching GUI dialog
42 Parameters:
44 input=name [required]
45 Name of input vector map
46 Or data source for direct OGR access
47 layer=string[,string,...]
49 Layer number or name
50 Vector features can have category values in different layers. This
51 number determines which layer to use. When used with direct OGR ac‐
52 cess this is the layer name.
53 Default: 1
54 type=string[,string,...]
56 Input feature type
57 Options: point, line, boundary, centroid, area, face, kernel
58 Default: point,line,centroid,face
59 ids=range
61 Feature ids (by default all features are processed)
62 Example: 1,3,7-9,13
63 output=name
65 Name for output vector map
66 option=string [required]
68 Action to be done
69 Options: add, del, chlayer, sum, report, print, layers, transfer
70 add: add a category to features without category in the given layer
71 del: delete category (cat=-1 to delete all categories of given
72 layer)
73 chlayer: change layer number (e.g. layer=3,1 changes layer 3 to
74 layer 1)
75 sum: add the value specified by cat option to the current category
76 value
77 report: print report (statistics), in shell style: layer type count
78 min max
79 print: print category values, layers are separated by ’|’, more
80 cats in the same layer are separated by ’/’
81 layers: print only layer numbers
82 transfer: copy values from one layer to another (e.g. layer=1,2,3
83 copies values from layer 1 to layer 2 and 3)
84 cat=integer
86 Category value
87 Default: 1
88 step=integer
90 Category increment
91 Default: 1
92
94 v.category attaches, copies, deletes or reports categories to/from/of
95 vector geometry objects. Further on, v.category adds a number given by
96 the cat option to categories of the selected layer. These categories
97 (IDs) are used to assign IDs or to group geometry objects into cate‐
98 gories (several different geometry objects share the same category).
99 These categories are also used to link geometry object(s) to attribute
100 records (from an attribute table linked to vector map).
101
103 Use v.to.db to upload related categories to a linked attribute table.
104 The type parameter specifies the type of geometry objects to which the
106 category is added; it is similar to an input filter - only the geometry
107 specified in ’type’ is processed.
108 If the type parameter is set to centroid and the option parameter set
110 to add, new categories will be added to existing centroids. Note how‐
111 ever, that new centroids cannot be created this way. To do so, they
112 must be added manually using wxGUI vector digitizer or by running
113 v.category with the type parameter set to area.
114 If categories are copied with option=transfer, a warning is issued if
116 categories already exit in the layer they are copied to. In this case
117 the user must make sure beforehand that copying categories from one
118 layer to another layer does not cause undesired grouping of different
119 geometry objects into the same categories. This can be avoided by spec‐
120 ifying only one layer. The module will then find the next free layer
121 number and copy categories to there. The new layer number is reported
122 at the end.
123 Areas are a special case because it is impossible to attach a cat to an
125 area without a centroid; in this case, the module places new centroids
126 in areas automatically for type=area.
127 The cat parameter is only used with option=add, option=sum and op‐
129 tion=del.
130 Categories can be deleted for the given layer with option=del. If cat
132 is set to -1, all categories for the given layer are deleted. If cat is
133 zero or positive, only this category value will be deleted. By default,
134 cat is set to 1 which means that only categories of value 1 will be
135 deleted.
136 With option=report, the module reports for each layer and type the to‐
138 tal number of categories, the minimum and the maximum category number.
139 If there are e.g. two lines with line 1 having category 1 and line 1
140 having categories 1 and 2, then there are a total of three category
141 values with minimum 1 and maximum 2.
142 The ids parameter specifies the list of feature IDs to which the opera‐
144 tion is performed; by default, all vector feature ids are processed.
145 The feature ID is an internal (unique) geometry ID that all vector
146 primitives possess, and is separate from any category the feature may
147 also possess. Use
148 v.edit map=inputname tool=select
149 to find out the geometry ids of certain features.
150
152 Report vector categories
153 v.category input=testmap option=report
154 LAYER/TABLE 1/testmap:
155 type count min max
156 point 0 0 0
157 line 1379 1 1379
158 boundary 0 0 0
159 centroid 0 0 0
160 area 0 0 0
161 all 1379 1 1379
162 Delete all vector categories in layer 1
164 v.category input=testmap output=outmap option=del cat=-1
165 Add vector categories in layer 1 with step=2
167 v.category input=outmap output=stepmap option=add step=2
168 # report
169 v.category input=stepmap option=report
170 LAYER/TABLE 1/outmap:
171 type count min max
172 point 0 0 0
173 line 1379 1 2757
174 boundary 0 0 0
175 centroid 0 0 0
176 area 0 0 0
177 all 1379 1 2757
178 Add categories/centroids to a vector map without categories
180 v.category input=wkt output=wktnew option=add
181 Results can be tested using d.what.vect.
182 Copy categories from layer 1 to layer 2,3,4,5,6,7 and 8
184 Existing layer will be overwritten, non-existing will be created.
185 v.category input=observer output=observer_new option=transfer layer=1,2,3,4,5,6,7,8
186 Print vector categories of given layer
188 Print vector categories from the first layer, only for feature ids
189 1-50.
190 v.category input=roads option=print layer=1 id=1-50
191
193 v.centroids, v.db.connect, v.edit, v.to.db
194
196 Radim Blazek, ITC-irst, Trento, Italy
197 Modified (the id parameter) by Martin Landa, FBK-irst (formerly
198 ITC-irst), Trento, Italy, 2008/02
199
201 Available at: v.category source code (history)
202 Accessed: Mon Jun 20 16:46:55 2022
204 Main index | Vector index | Topics index | Keywords index | Graphical
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207 © 2003-2022 GRASS Development Team, GRASS GIS 8.2.0 Reference Manual
209GRASS 8.2.0 v.category(1)