1v.to.db(1) Grass User's Manual v.to.db(1)
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6 v.to.db - Populates attribute values from vector features.
7
9 vector, attribute table, database, area, length, perimeter, coordi‐
10 nates, bounding box, category
11
13 v.to.db
14 v.to.db --help
15 v.to.db [-psc] map=name [layer=string] [type=string[,string,...]]
16 option=string columns=name[,name,...] [units=string]
17 [query_layer=string] [query_column=name] [separator=character]
18 [--help] [--verbose] [--quiet] [--ui]
19 Flags:
21 -p
22 Print only
23 -s
25 Only print SQL statements
26 -c
28 Print also totals for option length, area, or count
29 --help
31 Print usage summary
32 --verbose
34 Verbose module output
35 --quiet
37 Quiet module output
38 --ui
40 Force launching GUI dialog
41 Parameters:
43 map=name [required]
44 Name of vector map
45 Or data source for direct OGR access
46 layer=string
48 Layer number or name (write to)
49 Vector features can have category values in different layers. This
50 number determines which layer to use. When used with direct OGR
51 access this is the layer name.
52 Default: 1
53 type=string[,string,...]
55 Feature type
56 For coor valid point/centroid, for length valid line/boundary
57 Options: point, line, boundary, centroid
58 Default: point,line,boundary,centroid
59 option=string [required]
61 Value to upload
62 Options: cat, area, compact, fd, perimeter, length, count, coor,
63 start, end, sides, query, slope, sinuous, azimuth, bbox
64 cat: insert new row for each category if doesn’t exist yet
65 area: area size
66 compact: compactness of an area, calculated as
67 compactness = perimeter / (2 * sqrt(PI * area))
68 fd: fractal dimension of boundary defining a polygon, calculated as
69 fd = 2 * (log(perimeter) / log(area))
70 perimeter: perimeter length of an area
71 length: line length
72 count: number of features for each category
73 coor: point coordinates, X,Y or X,Y,Z
74 start: line/boundary starting point coordinates, X,Y or X,Y,Z
75 end: line/boundary end point coordinates, X,Y or X,Y,Z
76 sides: categories of areas on the left and right side of the bound‐
77 ary, ’query_layer’ is used for area category
78 query: result of a database query for all records of the geome‐
79 try(or geometries) from table specified by ’query_layer’ option
80 slope: slope steepness of vector line or boundary
81 sinuous: line sinuousity, calculated as line length / distance
82 between end points
83 azimuth: line azimuth, calculated as angle between North direction
84 and endnode direction at startnode
85 bbox: bounding box of area, N,S,E,W
86 columns=name[,name,...] [required]
88 Name of attribute column(s) to populate
89 Name of attribute column(s)
90 units=string
92 Units
93 Options: miles, feet, meters, kilometers, acres, hectares, radians,
94 degrees
95 query_layer=string
97 Query layer number or name (read from)
98 Vector features can have category values in different layers. This
99 number determines which layer to use. When used with direct OGR
100 access this is the layer name.
101 Default: 1
102 query_column=name
104 Name of attribute column used for ’query’ option
105 E.g. ’cat’, ’count(*)’, ’sum(val)’
106 separator=character
108 Field separator for print mode
109 Special characters: pipe, comma, space, tab, newline
110 Default: pipe
111
113 v.to.db loads vector map features or metrics into a database table, or
114 prints them (or the SQL queries used to obtain them) in a form of a
115 human-readable report. For uploaded/printed category values ’-1’ is
116 used for ’no category’ and ’null’/’-’ if category cannot be found or
117 multiple categories were found. For line azimuths ’-1’ is used for
118 closed lines (start equals end).
119
121 Measures of lengths and areas are always reported in meters, unless the
122 unit parameter is set. The units miles, feet, meters and kilometers
123 are square for option=area.
124 Feet and acre units are always reported in their common versions (i.e.
126 the International Foot, exactly 5280 feet in a mile), even when the
127 location’s standard map unit is the US Survey foot.
128 When calculating perimeters in Latitude-Longitude locations, the geo‐
130 desic distance between the vertices is used.
131 When using option=coor on a vector area map, only coordinates of cen‐
133 troids with unique category will be reported.
134 When using option=bbox on a vector area map with more than one feature
136 per category value, the results corresponds to the bounding box of all
137 features of same category taken together.
138 Line azimuth is calculated as angle from the North direction to the
140 line endnode direction at the line statnode. By default it’s reported
141 in decimal degrees (0-360, CW) but it also may be repored in radians
142 with unit=radians. Azimuth value -1 is used to report closed line with
143 it’s startnode and endnode being in same place. Azimuth values make
144 sense only if every vector line has only one entry in database (unique
145 CAT value).
146 If the module is apparently slow and the map attributes are stored in
148 an external DBMS such as PostgreSQL, it is highly recommended to create
149 an index on the key (category) column.
150 Uploading the vector map attributes to a database requires a table
152 attached to a given input vector layer. The print only (-p) mode
153 doesn’t require a table. Use db.execute or v.db.addtable to create a
154 table if needed.
155 Updating the table has to be done column-wise. The column must be
157 present in the table, except when using the print only (-p) mode. Use
158 db.execute or v.db.addcolumn to add new columns if needed.
159
161 Updating attribute tables
162 Upload category numbers to attribute table (used for new map):
163 v.to.db map=soils type=centroid option=cat
164 Upload polygon areas to corresponding centroid record in the attribute
166 table:
167 v.to.db map=soils type=centroid option=area columns=area_size unit=h
168 Upload line lengths (in meters) of each vector line to attribute table
170 (use v.category in case of missing categories):
171 v.to.db map=roads option=length type=line columns=linelength units=me
172 Upload x and y coordinates from vector geometry to attribute table:
174 v.to.db map=pointsmap option=coor columns=x,y
175 Upload x, y and z coordinates from vector geometry to attribute table:
177 v.to.db map=pointsmap option=coor columns=x,y,z
178 Transfer attributes from a character column (with numeric contents) to
180 a new integer column:
181 v.db.addcolumn usa_income_employment2002 col="FIPS_NUM integer"
182 v.to.db usa_income_employment2002 option=query columns=FIPS_NUM query_column=STATE_FIPS
183 Upload category numbers of left and right area, to an attribute table
185 of boundaries common for the areas:
186 # add categories for boundaries of the input vector map, in layer 2:
187 v.category soils out=mysoils layer=2 type=boundary option=add
188 # add a table with columns named "left" and "right" to layer 2 of the input
189 # vector map:
190 v.db.addtable mysoils layer=2 columns="left integer,right integer"
191 # upload categories of left and right areas:
192 v.to.db mysoils option=sides columns=left,right layer=2
193 # display the result:
194 v.db.select mysoils layer=2
195 Compute DL, the Fractal Dimension (Mandelbrot, 1982), of the boundary
197 defining a polygon based on the formula:
198 D = 2 * (log perimeter) / (log area):
199 g.copy vect=soils,mysoils
200 v.db.addcolumn mysoils col="d double precision"
201 v.to.db mysoils option=fd column="d"
202 g.region vector=mysoils res=50
203 v.to.rast input=mysoils output=soils_fd type=area use=attr attribute_column=d
204 r.colors map=soils_fd color=gyr
205 d.mon wx0
206 d.rast.leg soils_fd
207 d.vect mysoils type=boundary
208 Printing reports
210 Report x,y,z coordinates of points in the input vector map:
211 v.to.db -p bugsites option=coor type=point
212 Report all area sizes of the input vector map:
213 v.to.db -p soils option=area type=boundary units=h
214 Report all area sizes of the input vector map, in hectares, sorted by
216 category number (requires GNU sort utility installed):
217 v.to.db -p soils option=area type=boundary units=h | sort -n
218 Report all line lengths of the input vector map, in kilometers:
220 v.to.db -p roads option=length type=line units=k
221 Report number of features for each category in the input vector map:
223 v.to.db -p roads option=count type=line
224
226 d.what.vect, db.execute, v.category, v.db.addtable, v.db.addcolumn,
227 v.db.connect, v.distance, v.report, v.univar, v.what
228
230 · Mandelbrot, B. B. (1982). The fractal geometry of nature. New
231 York: W. H. Freeman.
232 · Xu, Y. F. & Sun, D. A. (2005). Geotechnique 55, No. 9, 691-695
234
236 Radim Blazek, ITC-irst, Trento, Italy
237 Line sinuousity implemented by Wolf Bergenheim
238 Last changed: $Date: 2017-01-29 15:04:26 +0100 (Sun, 29 Jan 2017) $
240
242 Available at: v.to.db source code (history)
243 Main index | Vector index | Topics index | Keywords index | Graphical
245 index | Full index
246 © 2003-2019 GRASS Development Team, GRASS GIS 7.6.0 Reference Manual
248GRASS 7.6.0 v.to.db(1)