## NAME

v.out.arc - Exports GRASS vector files to ARC/INFO's "ungenerate" file format.
(GRASS Vector Data Export Program)

## SYNOPSIS

v.out.arc
v.out.arc help
v.out.arc type=name vect=name arc_prefix=name

## DESCRIPTION

v.out.arc is a GRASS data export program that converts files in GRASS vector format to ARC/INFO's "Generate" file format. The companion program v.in.arc imports data in ARC/INFO's "Generate" format and converts them to GRASS vector format.

This program can be run either non-interactively or interactively. The program will be run non-interactively if the user specifies parameter values on the command line using the following format:

  v.out.arc type=name vect=name arc_prefix=name

Alternately, the user can simply type:

  v.out.arc

on the command line; in this case, the program will prompt the user for parameter values.

### Parameters:

type=name
  Coverage (feature) type.
  Options: polygon, line
vect=name
  The name of a GRASS vector file to be converted to ARC/INFO format.
arc_prefix=name
  A prefix to be assigned to the ARC/INFO-format files output by v.out.arc.

## INTERACTIVE MODE: USER PROMPTS

v.out.arc will prompt the user to enter the name of a GRASS vector file to be exported to ARC/INFO and for a filename prefix to be used in naming the files created by the program.

A GRASS vector file to be exported to ARC/INFO must either contain only linear features (i.e., have only line coverage) or contain only area edge features (i.e., have only polygon coverage). v.out.arc will begin by asking the user which type of coverage (line or polygon) is to be imported:

         COVERAGE TYPE
         Enter "polygon" or "line"
         Hit RETURN to cancel request
         >

The program then prompts the user for the name of the GRASS vector file to be converted to ARC/INFO format:

         VECTOR (DIGIT) FILENAME
         Enter 'list' for a list of existing binary vector files
         Hit RETURN to cancel request
         >

Next, the user is asked for a file-name prefix to be used in naming the output ARC/INFO Generate format files:

         ARC/INFO (GENERATE) FILENAME PREFIX
         Hit RETURN to cancel request
         >

The filename prefix will be used to name the various files that will be created for export to ARC/INFO. When labeled polygon coverage data are exported, three such files will be created: a lines file with the suffix .lin, a label-points file with the suffix .lab, and a label-text file with the suffix .txt. When line coverage data are exported, two such files will be created: a lines file with the suffix .lin, and a label-text file with the suffix .txt. Export of unlabeled polygon or line coverage data will result in creation of a lines file (.lin suffix) only. All exported files are stored in the current directory.
See the DATA FILE FORMATS section for more information on these files.

## EXAMPLE

Linear features and polygon data are made up of the series of arcs (aka, vectors) outlining their perimeters. The ARC/INFO Users' Guide, in its discussion of the Ungenerate command, explains how line and polygon coverage data can be created from files (like prefix.lin and prefix.pol) containing the geographic coordinates of these arcs, and from files (like prefix.lab) containing the geographic coordinates of label-points. Below is an example which illustrates the creation, within ARC/INFO, of a polygon coverage data file (named soils) from the files soils.pol and soils.lab.

       Arc: GENERATE SOILS
       Generate: INPUT soils.pol
       Generate: LINES
       Generating lines ...
       Generate: INPUT soils.lab
       Generate: POINTS
       Generating points ...
       Generate: QUIT
       Arc: _

The above example would create a polygon coverage data file named soils with label-points. The label-points would have ID numbers that correspond to the GRASS category values for the polygons in the coverage. The INFO portion of ARC/INFO can be used to associate these label-point ID numbers with descriptive text from the soils.txt file.

## DATA FILE FORMATS

LINES FILE, also know as prefix.lin or prefix.pol file:
This text file is a "Generate" format lines file. The lines option of the ARC/INFO Generate command can be used to read this file into ARC/INFO. Each line in the file has a unique line-ID number.

    101
    223343.62 218923.15
    223343.62 222271.06
    259565.31 222271.06
    259565.31 195577.37
    END
    102
    237862.53 203392.37
    244970.75 203744.28
    253137.66 195577.37
    259565.31 195577.37
    END
    103
    237862.53 203392.37
    237862.53 203744.28
    223343.62 218392.37
    END
    104
    239072.44 186200.56
    237862.53 187410.50
    237862.53 203392.37
    END
    END

LABEL-POINTS FILE, also known as prefix.lab file:
This text file will be created by v.out.arc if the vector file being exported represents a polygon coverage. prefix.lab consists of a list of label-point (x,y) coordinates, each with a unique label-point ID number.

    1 242777.81 211533.09
    2 243458.37 199282.28
    3 243458.37 195199.28

LABEL-TEXT FILE, also known as prefix.txt file:
In the case of polygon coverage data, this file associates an integer category value and a category label ("attribute") text string (containing no spaces) with each label-point ID number. In the case of line coverage data, this file associates an integer category value and an attribute text string with each line-ID number.

The first column is the row number (which is arbitrary), the second column contains the category value, the third column holds the line or label-point ID number, and the fourth column contains the attribute text string.

    1 4 1 Coniferous
    2 5 2 Deciduous
    3 2 3 Rangeland

## SEE ALSO

v.in.arc
v.support

## AUTHOR

Dave Johnson
DBA Systems, Inc.
10560 Arrowhead Drive
Fairfax, Virginia 22030

Last changed: $Date: 2002/01/25 05:45:35 $