v.extract <contrib>   GRASS Reference Manual  <contrib> v.extract



NAME
     v.extract - Selects vectors from an existing vector map and
     creates a new map containing only the selected vectors.
     (SCS GRASS Vector Program)

SYNOPSIS
     v.extract
     v.extract help
     v.extractFR [-dn] type=name input=name output=name new=value
	[list=range] [file=name]

DESCRIPTION
     v.extract allows a user to create a new vector map layer
     from an existing vector map layer.	 User provides the
     program with category numbers or option (n) names, input
     vector file name, an output vector name, and the type of
     input map.	 There is an option (d) to dissolve common
     boundaries between adjoining map areas in the same category
     list.  The user may specify a file containing category
     values or names.

     Note:

	  The dissolve option will work on only those areas which
	  are in the given category list.  If a map area is
	  inside (island) a listed category area and is NOT in
	  the given category list, its boundaries are output to
	  the resultant map.

COMMAND LINE OPTIONS
     Flags:

     -d		       Dissolve common boundaries (default is no)
		       .

     -n		       Use category names NOT category values.

     Parameters:

     type=name	       Select area, line, or site.
		       Options:	 area, line, site

     input=name	       Input vector map name.

     output=name       Output vector map name.

     new=value	       Enter 0 or a desired NEW category value.

     list=range	       Category ranges.
		       For example:  1, 3-8, 13
		       For example:  Abc, Def2, XyZ




GRASS 5.0beta6	      GRASS Development Team			1






v.extract <contrib>   GRASS Reference Manual  <contrib> v.extract



     file=name	       Text file name for category range/list .


EXAMPLE
	  $GISBASE/etc/v.extract -d list=1,2,3,4 &\
	  input=soils output=soil_groupa type=area new=1

     Produces a new vector area file soil_groupa containing
     'area' boundaries from soils with area category values of 1
     thru 4;  any common boundaries are dissolved, and all areas
     of the new map will be assigned category value 1.

	  $GISBASE/etc/v.extract -dn list=Abc,Def1,12A,WWd &\
	  input=soils output=soil_groupa type=area new=0

     Produces a new vector area file soil_groupa containing
     'area' boundaries from soils with area category names of
     Abc,Def1, 12A,WWd; these names correspond to values 1 thru 4
     of soils.	Any common boundaries are dissolved, all areas of
     the new map will be retain their original category values 1
     thru 4, in this case, since new was set to 0.

	  $GISBASE/etc/v.extract -n input=soils
	  output=soil_groupa &\
	  type=area new=1 file=sample

     Produces a new vector area file soil_groupa containing
     'area' boundaries from soils.  No common boundaries are
     dissolved, all areas of the new map will be assigned
     category value 1.	The "names" (-n option) can be found in
     the file sample of the current directory.

	  The format for "sample" is:
	  Abc
	  Def1
	  12A
	  WWd

AUTHOR
     R.L. Glenn, USDA, SCS, NHQ-CGIS


NOTICE
     This program is part of the contrib section of the GRASS
     distribution.  As such, it is externally contributed code
     that has not been examined or tested by the Office of GRASS
     Integration.








2		      GRASS Development Team	   GRASS 5.0beta6