v.in.ascii(1grass) GRASS GIS User's Manual v.in.ascii(1grass)
NAME
v.in.ascii - Creates a vector map from an ASCII points file or ASCII
vector file.
KEYWORDS
vector, import, ASCII, level1, area, line, point
SYNOPSIS
v.in.ascii
v.in.ascii --help
v.in.ascii [-zentbri] input=name output=name [format=string] [sepa-
rator=character] [text=character] [skip=integer] [columns=string]
[x=integer] [y=integer] [z=integer] [cat=integer] [--overwrite]
[--help] [--verbose] [--quiet] [--ui]
Flags:
-z
Create 3D vector map
-e
Create a new empty vector map and exit. Nothing is read from input.
-n
Do not expect a header when reading in standard format
-t
Do not create table in points mode
-b
Do not build topology
Do not build topology in points mode
-r
Only import points falling within current region (points mode)
-i
Ignore broken line(s) in 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 file to be imported
’-’ for standard input
output=name [required]
Name for output vector map
format=string
Input file format
Options: point, standard
Default: point
point: simple x,y[,z] list
standard: GRASS vector ASCII format
separator=character
Field separator
Special characters: pipe, comma, space, tab, newline
Default: pipe
text=character
Text delimiter
Special characters: doublequote, singlequote, none
skip=integer
Number of header lines to skip at top of input file (points mode)
Default: 0
columns=string
Column definition in SQL style (points mode)
For example: ’x double precision, y double precision, cat int, name
varchar(10)’
x=integer
Number of column used as x coordinate (points mode)
First column is 1
Default: 1
y=integer
Number of column used as y coordinate (points mode)
First column is 1
Default: 2
z=integer
Number of column used as z coordinate (points mode)
First column is 1. If 0, z coordinate is not used
Default: 0
cat=integer
Number of column used as category (points mode)
First column is 1. If 0, unique category is assigned to each row
and written to new column ’cat’
Default: 0
DESCRIPTION
v.in.ascii converts a vector map in GRASS ASCII vector format to a vec-
tor map in binary format. The module may import two formats:
• standard contains all data types, each coordinate on one row
• point (default) reads only points, each point defined on one
row. Values are separated by a user-definable delimiter. If the
columns option is not defined, default names are used. It is
possible to specify the column order for the x,y,z coordinates
and category values.
v.out.ascii performs the function of v.in.ascii in reverse; i.e., it
converts vector maps in binary format to GRASS ASCII vector format.
These two companion programs are useful both for importing and export-
ing vector maps between GRASS and other software, and for transferring
data between machines.
NOTES
The input is read from the file specified by the input option or from
standard input.
The field separator may be a character, the word ’tab’ (or ’\t’) for
tab, ’space’ (or ’ ’) for a blank, or ’comma’ (or ’,’) for a comma.
An attribute table is only created if it is needed, i.e. when at least
one attribute column is present in the input file besides geometry col-
umns. The attribute column will be auto-scanned for type, but may be
explicitly declared along with the geometry columns using the columns
parameter.
Use the -z flag to convert ASCII data into a 3D vector map.
In special cases of data import, such as the import of large LIDAR
datasets (millions of data points), it may be necessary to disable
topology support (vector level 1) due to memory constraints. This is
done with the -b flag. As only very few vector modules support points
data processing at vector level 1, usually topology is required (vector
level 2). Therefore it is recommended that the user first try to import
the data without creating a database (the -t flag) or within a subre-
gion (the -r flag) before resorting to the disabling of topology.
If old version is requested, the output files from v.out.ascii is
placed in the $LOCATION/$MAPSET/dig_ascii/ and $LOCA-
TION/$MAPSET/dig_att directory.
Import of files without category column
If the input file does not contain a category column, there is the pos-
sibility to auto-generate these IDs (categories). To automatically add
an additional column named ’cat’, the cat parameter must be set to the
virtual column number 0 (cat=0). This is the default action if the cat
parameter is not set.
Importing from a spreadsheet
Data may be imported from many spreadsheet programs by saving the
spreadsheet as a comma separated variable (.csv) text file, and then
using the separator=’,’ or separator=comma option with v.in.ascii in
points mode. If the input file contains any header lines, such as col-
umn headings, the skip parameter should be used. These skipped header
lines will be written to the map’s history file for later reference
(read with v.info -h). The skip option only works in points mode.
Any line starting with the hash character (’#’) will be treated as a
comment and skipped completely if located in the main data file. If lo-
cated in the header, as defined by the skip parameter, it will be
treated as a header line and written to the history file.
Import of sexagesimal degree (degree, minutes, seconds, DMS)
The import of DMS formatted degrees is supported (in this case no sign
but N/S, E/W characters are used to indicate the hemispheres). While
the positions are internally translated into decimal degrees during the
import, the original DMS values are maintained in the attribute table.
This requires both the latitude and the longitude columns to be defined
as varchar(), not as numbers. A warning will be issued which can be
ignored. See GRASS ASCII vector format specification for details.
Importing only selected columns
Although v.in.ascii doesn’t have an option to specify which columns
should be imported, you can use a shell filter to achieve the same ef-
fect, e.g.:
# Print out the column number for each field, supposing the file has a header
head -1 input_file | tr ’<the_field_separator_character>’ ’\n’ | cat -n
# From the listing, select the columns you want and feed them to v.in.ascii
# use input=- to read from stdin
cut -d<the_field_separator_character> -f<comma-separated_list_of_columns> input_file | v.in.ascii in=- <your_options>
EXAMPLES
Example 1a) - standard format mode
Sample ASCII polygon vector map for ’standard’ format mode. The two
areas will be assigned categories 20 and 21. For details on the struc-
ture of standard format data files see the second reference at the bot-
tom of this page.
echo "ORGANIZATION: GRASS Development Team
DIGIT DATE: 1/9/2005
DIGIT NAME: -
MAP NAME: test
MAP DATE: 2005
MAP SCALE: 10000
OTHER INFO: Test polygons
ZONE: 0
MAP THRESH: 0.500000
VERTI:
B 6
5958812.48844435 3400828.84221011
5958957.29887089 3400877.11235229
5959021.65906046 3400930.7458436
5959048.47580612 3400973.65263665
5959069.92920264 3401032.64947709
5958812.48844435 3400828.84221011
C 1 1
5958952.42189184 3400918.23126419
1 20
B 4
5959010.9323622 3401338.36037757
5959096.7459483 3401370.54047235
5959091.38259917 3401450.99070932
5959010.9323622 3401338.36037757
C 1 1
5959063.08352122 3401386.98533277
1 21" | v.in.ascii in=- format=standard output=test_polygons
Example 1b) - standard format mode
Sample ASCII 3D line vector map for ’standard’ format mode with simpli-
fied input (note the space field separator). Note the -z flag indicat-
ing 3D vector input, and the -n flag indicating no vector header should
be expected from the input file.
echo "L 5 1
591336 4927369 1224
594317 4925341 1292
599356 4925162 1469
602396 4926653 1235
607524 4925431 1216
1 321 " | v.in.ascii -zn in=- out=line3d format=standard
This can be used to create a vector line of a GPS track: the GPS points
have to be stored into a file with a preceding ’L’ and the number of
points (per line).
Example 2 - point format mode
Generate a 2D points vector map ’coords.txt’ as ASCII file:
1664619|5103481
1664473|5095782
1664273|5101919
1663427|5105234
1663709|5102614
Import into GRASS:
v.in.ascii input=coords.txt output=mymap
As the cat option is set to 0 by default, an extra column ’cat’ con-
taining the category numbers will be auto-generated.
Example 3 - point format mode
Generate a 2D points vector map ’points.dat’ as ASCII file:
1|1664619|5103481|studna
2|1664473|5095782|kadibudka
3|1664273|5101919|hruska
4|1663427|5105234|mysi dira
5|1663709|5102614|mineralni pramen
Import into GRASS:
cat points.dat | v.in.ascii in=- out=mypoints x=2 y=3 cat=1 \
columns=’cat int, x double precision, y double precision, label varchar(20)’
The module is reading from standard input, using the default ’|’ (pipe)
delimiter.
Example 4 - point format mode - CSV table
Import of a 3D points CSV table (’points3d.csv’) with attributes:
"num","X","Y","Z","T"
1,2487491.643,5112118.33,120.5,18.62
2,2481985.459,5109162.78,123.9,18.46
3,2478284.289,5105331.04,98.3,19.61
Import into GRASS:
# import: skipping the header line, categories generated automatically,
# column names defined with type:
v.in.ascii -z in=points3d.csv out=mypoints3D separator=comma \
columns="num integer, x double precision, y double precision, z double precision, temp double precision" \
x=2 y=3 z=4 skip=1
# verify column types
v.info -c mypoints3D
# verify table content
v.db.select mypoints3D
Example 5 - point format mode
Generating a 3D points vector map from DBMS (idcol must be an integer
column):
echo "select east,north,elev,idcol from mytable" | db.select -c | v.in.ascii in=- -z out=mymap
With in=-, the module is reading from standard input, using the default
’|’ (pipe) delimiter.
The import works for 2D maps as well (no elev column and no ’-z’ flag).
Example 6 - point format mode
Generate a 3D points vector map ’points3d.dat’ with attributes as ASCII
file:
593493.1|4914730.2|123.1|studna|well
591950.2|4923000.5|222.3|kadibudka|outhouse
589860.5|4922000.0|232.3|hruska|pear
590400.5|4922820.8|143.2|mysi dira|mouse hole
593549.3|4925500.7|442.6|mineralni pramen|mineral spring
600375.7|4925235.6|342.2|kozi stezka|goat path
Import into GRASS:
#As the ’cat’ option is set to 0 by default, an extra column ’cat’
#containing the IDs will be auto-generated (no need to define that):
cat points3d.dat | v.in.ascii in=- -z z=3 cat=0 out=mypoints3D \
columns=’x double precision, y double precision, z double precision, \
label_cz varchar(20), label_en varchar(20)’
v.info -c mypoints3D
v.info mypoints3D
Example 7 - point format mode
Generate points file by clicking onto the map:
#For LatLong locations:
d.where -d -l | awk ’{printf "%f|%f|point\n", $1, $2}’ | v.in.ascii in=- out=points \
columns=’x double precision, y double precision, label varchar(20)’
#For other projections:
d.where | awk ’{printf "%f|%f|point\n", $1, $2}’ | v.in.ascii in=- out=points \
columns=’x double precision, y double precision, label varchar(20)’
The ’point’ string (or some similar entry) is required to generate a
database table. When simply piping the coordinates (and optionally
height) without additional column(s) into v.in.ascii, only the vector
map geometry will be generated.
Example 8 - point format mode
Convert ground control points into vector points:
cat $MAPSET/group/$GROUP/POINTS | v.in.ascii in=- out=$GROUP_gcp separator=space skip=3 \
col=’x double precision, y double precision, x_target double precision, \
y_target double precision, ok int’
REFERENCES
SQL command notes for creating databases
GRASS ASCII vector format specification
SEE ALSO
db.execute, r.in.ascii, r.in.poly, r.in.xyz, v.build, v.build.poly-
lines, v.centroids, v.clean, v.db.connect, v.import, v.info,
v.in.lines, v.in.mapgen, v.out.ascii
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
SOURCE CODE
Available at: v.in.ascii source code (history)
Accessed: unknown
Main index | Vector index | Topics index | Keywords index | Graphical
index | Full index
© 2003-2022 GRASS Development Team, GRASS GIS 7.8.7 Reference Manual
GRASS 7.8.7 v.in.ascii(1grass)
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