v.out.ascii(1)

NAME
v.out.ascii - Exports a vector map to a GRASS ASCII vector representation.
By default only features with category are exported. To export all features use ’layer=-1’.

KEYWORDS
vector, export, output, ASCII

SYNOPSIS
v.out.ascii
v.out.ascii --help
v.out.ascii [-ocr] input=name [layer=string] [type=string[,string,...]] [output=name] [columns=name[,name,...]] [cats=range] [where=sql_query] format=string [separator=character] [precision=integer] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

  Flags:

-o
    Create old (version 4) ASCII file

-c
    Include column names in output (points mode)

-r
    Only export points falling within current 3D region (points mode)

--overwrite
    Allow output files to overwrite existing files

--help
    Print usage summary

--verbose
    Verbose module output

--quiet
    Quiet module output

--ui
    Force launching GUI dialog

  Parameters:

input=name [required]
    Name of input vector map
    Or data source for direct OGR access

layer=string
    Layer number or name (’-1’ for all layers)
    A single vector map can be connected to multiple database tables. This number determines which table to use. When used with direct OGR access this is the layer name.
    Default: 1

type=string[,string,...]
    Input feature type
    Options: point, line, boundary, centroid, area, face, kernel
    Default: point,line,boundary,centroid,area,face,kernel

output=name
    Name for output ASCII file or ASCII vector name if ’-o’ is defined
    If not given or ’-’ then standard output

columns=name[,name,...]
    Name of attribute column(s) to be exported (point mode)
    "*" for all columns

cats=range
    Category values
    Example: 1,3,7-9,13

where=sql_query
    WHERE conditions of SQL statement without ’where’ keyword
    Example: income < 1000 and population >= 10000

format=string [required]
    Output format
    Options: point, standard, wkt
    Default: point
    point: Simple point format (point per row)
    standard: GRASS ASCII vector format
    wkt: OGC well-known text

separator=character
    Field separator
    Field separator (points mode)
    Default: pipe

precision=integer
    Number of significant digits (floating point only)
    Options: 0-32
    Default: 8

DESCRIPTION
v.out.ascii converts a GRASS vector map in binary format to a GRASS vector map in ASCII format. Using flag -o v.out.ascii output will be in old (version 4) ASCII format.

If the output parameter is not given then the data is sent to standard output.

NOTES
The v.in.ascii module performs the function of v.out.ascii in reverse; i.e. it converts vector maps in ASCII format to their binary format. These two companion modules are useful both for importing and exporting vector maps between GRASS and other software, and for transferring data between machines.

If old version is requested, the output files from v.out.ascii is placed in the $LOCATION/$MAPSET/dig_ascii/ and $LOCATION/$MAPSET/dig_att directory.

If layer > 0 then only features with a category number will be exported. Use v.category to add them if needed or define layer=-1 to export also features without category.

v.out.ascii in the old version mode (-o) does not copy the dig_cats file associated with the binary vector input map to the new output file name. The user must copy the dig_cats file to the new output name if this is desired (e.g. using the UNIX cp command).

It is possible to output the coordinates of vertices in a non-points vector feature by first converting the vector feature to a points map with v.to.points and then exporting with v.out.ascii in points mode.

EXAMPLES

  Standard mode
See ASCII format specification.

v.out.ascii input=quads format=standard
ORGANIZATION: US Army Const. Eng. Rsch. Lab
DIGIT DATE:   May 1987
DIGIT NAME:   grass
MAP NAME:     Quads
MAP DATE:     May 1987
MAP SCALE:    24000
OTHER INFO:
ZONE:         13
MAP THRESH:   18.288000
VERTI:
B  4
 599587.1820962 4914067.53414294
 589639.15126831 4913922.5687301
 589440.96838162 4927803.62500018
 599375.87959179 4927959.83330436
B  2
 599375.87959179 4927959.83330436
 599587.1820962 4914067.53414294
B  4
 599587.1820962 4914067.53414294
 609541.5508239 4914236.0597482
 609316.10665227 4928116.8490555
 599375.87959179 4927959.83330436
C  1 1
 594125.63    4921115.58
 1     1
C  1 1
 604433.84    4921087.1
 1     2

  Point mode

v.out.ascii input=quads format=point
594125.63|4921115.58|1
604433.84|4921087.1|2

Print also selected attributes:

v.out.ascii input=geodetic_pts format=point where="cat > 5 and cat <= 8" columns=GEOD_NAME
573638.06289275|271623.25042595|6|27 WC 6
574416.81289275|274116.65542595|7|27 WC 7
575301.31189275|275303.81342595|8|27 WC 8

To print all attributes type columns=*:

v.out.ascii input=geodetic_pts format=point where="cat > 5 and cat <= 8" columns=*
573638.06289275|271623.25042595|6|6|0.00000000|0.00000000|6|6|27 WC 6|573638.09200000|271623.24100000|0.00|0|1.00000000|1.00000000
574416.81289275|274116.65542595|7|7|0.00000000|0.00000000|7|7|27 WC 7|574416.84100000|274116.64900000|0.00|0|1.00000000|1.00000000
575301.31189275|275303.81342595|8|8|0.00000000|0.00000000|8|8|27 WC 8|575301.30600000|275303.82600000|0.00|0|1.00000000|1.00000000

  WKT mode
WKT is abbreviation for Well-known text.

v.out.ascii input=quads format=wkt
POLYGON((599587.18209620 4914067.53414294, 589639.15126831 4913922.56873010,
         589440.96838162 4927803.62500018, 599375.87959179 4927959.83330436,
         599587.18209620 4914067.53414294))
POLYGON((599587.18209620 4914067.53414294, 599375.87959179 4927959.83330436,
         609316.10665227 4928116.84905550, 609541.55082390 4914236.05974820,
         599587.18209620 4914067.53414294))

SEE ALSO
v.category, v.in.ascii, v.to.points

GRASS ASCII vector format specification
GRASS SQL interface

AUTHORS
Michael Higgins, U.S. Army Construction Engineering Research Laboratory
James Westervelt, U.S. Army Construction Engineering Research Laboratory
Radim Blazek, ITC-Irst, Trento, Italy
Attribute selection added by Martin Landa, Czech Technical University in Prague, Czech Republic (2008/12)

SOURCE CODE

Available at: v.out.ascii source code (history)

Accessed: Wednesday Jul 09 13:13:47 2025

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