v.to.db(1)

1v.to.db(1)                    Grass User's Manual                   v.to.db(1)
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NAME

6       v.to.db  - Populate database values from vector features.
7       Load values from vector to database. For uploaded/printed category val‐
8       ues '-1' is used for 'no category' and 'null'/'-' if category cannot be
9       found or multiple categories were found.
10

KEYWORDS

12       vector, database, attribute table
13

SYNOPSIS

15       v.to.db
16       v.to.db help
17       v.to.db  [-psc]  map=name  [type=string[,string,...]]   [layer=integer]
18       [qlayer=integer]       option=string       [units=string]         [col‐
19       umn=string[,string,...]]   [qcolumn=string]   [--verbose]  [--quiet]
20
21   Flags:
22       -p
23           Print only
24
25       -s
26           Only print sql statements
27
28       -c
29           In print mode prints totals for options: length,area,count
30
31       --verbose
32           Verbose module output
33
34       --quiet
35           Quiet module output
36
37   Parameters:
38       map=name
39           Name of input vector map
40
41       type=string[,string,...]
42           Type
43           Type  of  elements (for coor valid point/centroid, for length valid
44           line/boundary)
45           Options: point,line,boundary,centroid
46           Default: point,line,boundary,centroid
47
48       layer=integer
49           Layer number
50           A single vector map can be connected to multiple  database  tables.
51           This number determines which table to use.
52           Default: 1
53
54       qlayer=integer
55           Layer number
56           Query layer. Used by 'query' option.
57           Default: 1
58
59       option=string
60           Value to upload
61           Options:                                   cat,area,compact,perime‐
62           ter,length,count,coor,start,end,sides,query,slope
63           cat: insert new row for each category if doesn't exist yet
64           area: area size
65           compact: compactness  of  an  area,  calculated  as  compactness  =
66           perimeter / (2 * sqrt(PI * area))
67           perimeter: perimeter length of an area
68           length: line length
69           count: number of features for each category
70           coor: point coordinates, X,Y or X,Y,Z
71           start: line/boundary starting point coordinates, X,Y or X,Y,Z
72           end: line/boundary end point coordinates, X,Y or X,Y,Z
73           sides: categories of areas on the left and right side of the bound‐
74           ary, 'qlayer' is used for area category
75           query: result of a database query for all  records  of  the  geome‐
76           try(or geometries) from table specified by 'qlayer' option
77           slope: slope steepness of vector line or boundary
78
79       units=string
80           Units
81           mi(les),f(eet),me(ters),k(ilometers),a(cres),h(ectares)
82           Options: mi,miles,f,feet,me,meters,k,kilometers,a,acres,h,hectares
83
84       column=string[,string,...]
85           Column(s)
86
87       qcolumn=string
88           Query column used for 'query' option
89           E.g. 'cat', 'count(*)', 'sum(val)'
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DESCRIPTION

92       v.to.db  loads vector map features or metrics into a database table, or
93       prints them (or the SQL queries used to obtain them) in  a  form  of  a
94       human-readable report.
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NOTES

97       The   units   miles,   feet,  meters  and  kilometers  are  square  for
98       option=area.
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100       Feet and acre units are always reported in their common versions  (i.e.
101       the  International  Foot,  exactly  5280 feet in a mile), even when the
102       location's standard map unit is the US Survey foot.
103
104       When calculating perimeters in Latitude-Longitude locations,  the  geo‐
105       desic distance between the vertices is used.
106
107       When  using  option=coor on a vector area map, only coordinates of cen‐
108       troids with unique category will be reported.
109
110       If the module is apparently slow and the map attributes are  stored  in
111       an external DBMS such as PostgreSQL, it is highly recommended to create
112       an index on the key (category) column.
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114       Uploading the vector map attributes to  a  database  requires  a  table
115       attached  to  a  given  input  vector  layer.  The print only (-p) mode
116       doesn't require a table. Use db.execute or v.db.addtable  to  create  a
117       table if needed.
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119       Updating  the  table  has  to  be  done column-wise. The column must be
120       present in the table, except when using the print only (-p)  mode.  Use
121       db.execute or v.db.addcol to add new columns if needed.
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EXAMPLES

124   Updating attribute tables
125       Upload category numbers to attribute table (used for new map):
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127       v.to.db map=soils type=area option=cat
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129
130       Upload area sizes of each polygon to attribute table:
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132       v.to.db map=soils type=area option=area col=area_size unit=h
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134
135       Upload  line lengths (in meters) of each vector line to attribute table
136       (use v.category in case of missing categories):
137
138       v.to.db map=roads option=length type=line col=linelength units=me
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140
141       Upload x and y coordinates from vector geometry to attribute table:
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143       v.to.db map=pointsmap option=coor col=x,y
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145
146       Upload x, y and z coordinates from vector geometry to attribute table:
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148       v.to.db map=pointsmap option=coor col=x,y,z
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150
151       Transfer attributes from a character column (with numeric contents)  to
152       a new integer column:
153
154       v.db.addcol usa_income_employment2002 col="FIPS_NUM integer"
155       v.to.db     usa_income_employment2002     option=query     col=FIPS_NUM
156       qcol=STATE_FIPS
157
158
159       Upload category numbers of left and right area, to an  attribute  table
160       of boundaries common for the areas:
161
162       # add categories for boundaries of the input vector map, in layer 2:
163       v.category soils out=mysoils layer=2 type=boundary option=add
164       #  add  a table with columns named "left" and "right" to layer 2 of the
165       input
166       # vector map:
167       v.db.addtable mysoils layer=2 col="left integer,right integer"
168       # upload categories of left and right areas:
169       v.to.db mysoils option=sides col=left,right layer=2
170       # display the result:
171       v.db.select mysoils layer=2
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173
174   Printing reports
175       Report x,y,z coordinates of points in the input vector map:
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177       v.to.db -p bugsites option=coor type=point
178        Report all area sizes of the input vector map:
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180       v.to.db -p soils option=area type=boundary units=h
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183       Report all area sizes of the input vector map, in hectares,  sorted  by
184       category number (requires GNU sort utility installed):
185
186       v.to.db -p soils option=area type=boundary units=h | sort -n
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188
189       Report all line lengths of the input vector map, in kilometers:
190
191       v.to.db -p roads option=length type=line units=k
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193
194       Report number of features for each category in the input vector map:
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196       v.to.db -p roads option=count type=line
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AUTHOR

204       Radim Blazek
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206       Last changed: $Date: 2007-11-20 10:34:59 +0100 (Tue, 20 Nov 2007) $
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208       Full index
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210       © 2003-2008 GRASS Development Team
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214GRASS 6.3.0                                                         v.to.db(1)