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.
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
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
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