
NAME
v.to.db - Load values from vector to database. In uploaded/printed category values '-1' is used for 'no category' and 'null'/'-' if category cannot be found or multiple categories were found.
SYNOPSIS
v.to.db
v.to.db help
v.to.db [-psc] map=name [type=string[,string,...]] [layer=integer] [qlayer=integer] option=string [units=string] [column=string[,string,...]] [qcolumn=string]
Flags:
- -p
- print only
- -s
- only print sql statements
- -c
- In print mode prints totals for options: length,area,count
Parameters:
- map=name
- Name of input vector map
- type=string[,string,...]
- Type of elements (for coor valid point/centroid, for length valid line/boundary)
- Options: point,line,boundary,centroid
- Default: point,line,boundary,centroid
- layer=integer
- Layer number
- Default: 1
- qlayer=integer
- Query layer. Used by 'query' option.
- Default: 1
- option=string
- Value to upload
- Options: cat,area,compact,perimeter,length,count,coor,start,end,sides,query
- cat: insert new row for each category if doesn't exist yet
- area: area size
- compact: compactness of an area, calculated as
compactness = perimeter / 2 * sqrt(PI * area)
- perimeter: perimeter length of an area
- length: line length
- count: number of features for each category
- coor: point coordinates, X,Y or X,Y,Z
- start: line/boundary starting point coordinates, X,Y or X,Y,Z
- end: line/boundary end point coordinates, X,Y or X,Y,Z
- sides: categories of areas on the left and right side of the boundary, 'qlayer' is used for area category
- query: result of a database query for all records of the geometry(or geometries) from table specified by 'qlayer' option
- units=string
- mi(les),f(eet),me(ters),k(ilometers),a(cres),h(ectares)
- Options: mi,miles,f,feet,me,meters,k,kilometers,a,acres,h,hectares
- column=string[,string,...]
- column(s)
- qcolumn=string
- Query column used for 'query' option. E.g. 'cat', 'count(*)', 'sum(val)'
DESCRIPTION
v.to.db load values from vector map to database.
NOTES
The units 'miles', 'feet', 'meters' and 'kilometers' are square
for option=area.
When using option=coor on a vector area map,
only coordinates of centroids with unique category will be reported.
When calculating perimeters in Latitude-Longitude locations, the
geodesic distance between the vertices is used.
EXAMPLES
Updating attribute tables
Note: Uploading of the attributes of a vector map to the DBMS has to be done
column-wise. The column must be present in the table
(use db.execute to add a new column if needed).
Upload category numbers to attribute table (used for new map):
v.to.db map=soils type=area option=cat
Upload area sizes of each polygon to attribute table:
v.to.db map=soils type=area option=area col=area_size unit=h
Upload line lengths (in meters) of each vector line to attribute table
(use v.category in case of missing categories):
v.to.db map=roads option=length type=line col=linelength units=me
Upload x and y coordinates from vector geometry to attribute table:
v.to.db map=pointsmap option=coor col=x,y
Upload x, y and z coordinates from vector geometry to attribute table:
v.to.db map=pointsmap option=coor col=x,y,z
Transfer of attributes from character column (with numeric contents) to new
integer column:
v.db.addcol usa_income_employment2002 col="FIPS_NUM integer"
v.to.db usa_income_employment2002 option=query col=FIPS_NUM qcol=STATE_FIPS
Upload category numbers of left/right polygons neighboring boundaries to attribute table:
# add boundary categories into geometry at layer 2:
v.category soils out=mysoils layer=2 type=boundary option=add
# add table with left/right column to layer 2:
v.db.addtable mysoils layer=2 col="left integer,right integer"
# upload categories of left/right polygons:
v.to.db mysoils option=sides col=left,right layer=2
# display the result:
v.db.select mysoils layer=2
Printing reports
Report all area sizes of a map:
v.to.db -p soils option=area type=boundary units=h
Report all area sizes of a map, sorted by category number:
v.to.db -p soils option=area type=boundary units=h | sort -n
Report all line lengths of a map:
v.to.db -p roads option=length type=line units=k
Report number of features for each category in map:
v.to.db -p roads option=count type=line
NOTES
If the module is apparently slow and the map attributes are stored
in an external DBMS such as PostgreSQL, it is highly recommended to
create an index on the key (category) column.
SEE ALSO
v.category,
v.what.vect
AUTHOR
Radim Blazek
Last changed: $Date: 2005/11/30 15:26:16 $
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