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NAME

v.db.droprow - Removes a vector object (point, line, area, face etc.) from a vector map through attribute selection.

KEYWORDS

vector, database, attribute table

SYNOPSIS

v.db.droprow
v.db.droprow help
v.db.droprow input=name output=name [layer=integer] where=string [--overwrite] [--verbose] [--quiet]

Flags:

--overwrite
Allow output files to overwrite existing files
--verbose
Verbose module output
--quiet
Quiet module output

Parameters:

input=name
Vector map for which to drop vector objects
output=name
Name for output vector map
layer=integer
Layer of attribute table to use for selection
Default: 1
where=string
WHERE conditions for vector delete, without 'where' keyword (e.g. "elevation IS NULL")

DESCRIPTION

v.db.droprow removes vector object(s) (point, line, area, face etc.) from a vector map through attribute selection in the table connected to the given vector map. It automatically checks the connection for the specified layer.

NOTES

v.db.droprow is a front-end to v.extract (reverse selection) to allow easier usage. The existing database connection(s) can be verified with v.db.connect.

EXAMPLES

Dropping all vector points without elevation attribute (Spearfish data set):
g.region rast=elevation.10m
v.random output=rand5k_elev n=5000 

v.db.addtable map=rand5k_elev column="elevation double precision"
v.what.rast vect=rand5k_elev rast=elevation.10m column=elevation

# verify absence of some elevation attributes ("number of NULL attributes"):
v.univar rand5k_elev type=point column=elevation

# Remove all vector points lacking elevation attribute
v.db.droprow rand5k_elev output=rand5k_elev_filt where="elevation IS NULL"

# verify:
v.univar rand5k_elev_filt type=point column=elevation

SEE ALSO

db.droptable, db.execute, v.db.addcolumn, v.db.addtable, v.db.connect, v.db.dropcol, v.db.droptable, v.db.select, v.db.update

AUTHOR

Markus Neteler

Last changed: $Date: 2009-11-26 13:51:15 -0800 (Thu, 26 Nov 2009) $


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