Geografic-Information-System/vector/v.in.ascii/v.in.ascii.html

<h2>DESCRIPTION</h2>

<em>v.in.ascii</em> converts a vector map
in <a href="vectorascii.html">GRASS ASCII vector format</a> to a
vector map in binary format. The module may import two formats:
<ul>
<li><b>standard</b> contains all data types, each coordinate on one row</li>
<li><b>point</b> (default) reads only points, each point defined on
  one row. Values are separated by a user-definable delimiter. If
  the <b>columns</b> 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.</li>
</ul>

<p><em><a href="v.out.ascii.html">v.out.ascii</a></em> performs the
function of <em>v.in.ascii</em> 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 exporting vector maps between GRASS
and other software, and for transferring data between machines.

<h2>NOTES</h2>
 
The input is read from the file specified by the <b>input</b> option or
from standard input.

<p>The field separator may be a character, the word '<tt>tab</tt>'
(or '<tt>\t</tt>') for tab, '<tt>space</tt>' (or '&nbsp;') for a blank,
or '<tt>comma</tt>' (or ',') for a comma.

<p>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 columns. The attribute column will be auto-scanned for type, but
may be explicitly declared along with the geometry columns using the
<b>columns</b> parameter.

<p>Use the <b>-z</b> flag to convert ASCII data into a 3D vector map.

<p>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>-b</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 <b>-t</b> flag) or
within a subregion (the <b>-r</b> flag) before resorting to the
disabling of topology.

<p>If old version is requested, the <b>output</b> files
from <em><a href="v.out.ascii.html">v.out.ascii</a></em> is placed in
the <tt>$LOCATION/$MAPSET/dig_ascii/</tt>
and <tt>$LOCATION/$MAPSET/dig_att</tt> directory.

<h3>Import of files without category column</h3>

If the input file does not contain a category column, there is the
possibility to auto-generate these IDs (categories). To automatically
add an additional column named 'cat', the <b>cat</b> parameter must be
set to the virtual column number 0 (<tt>cat=0</tt>). This is the
default action if the <b>cat</b> parameter is not set.

<h3>Importing from a spreadsheet</h3>

Data may be imported from many spreadsheet programs by saving the
spreadsheet as a comma separated variable (.csv) text file, and then
using the <b>separator=','</b> or <b>separator=comma</b> option
with <em>v.in.ascii</em> in <b>points</b> mode.  If the input file
contains any header lines, such as column headings, the
<b>skip</b> parameter should be used. These skipped header lines will
be written to the map's history file for later reference (read with
<tt>v.info&nbsp;-h</tt>). The skip option only works in <b>points</b> mode.

<p>Any line starting with the hash character ('<tt>#</tt>') will be treated as
a comment and skipped completely if located in the main data file. If located
in the header, as defined by the <b>skip</b> parameter, it will be treated as
a header line and written to the history file.

<h3>Import of sexagesimal degree (degree, minutes, seconds, DMS)</h3>

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 <tt>varchar()</tt>, not as numbers.  A warning will be
issued which can be ignored. See <a href="vectorascii.html">GRASS
ASCII vector format specification</a> for details.

<h3>Importing only selected columns</h3>
Although <em>v.in.ascii</em> doesn't have an option to specify which columns
should be imported, you can use a shell filter to achieve the same effect,
e.g.:

<div class="code"><pre>
# Print out the column number for each field, supposing the file has a header
head -1 input_file | tr '&lt;the_field_separator_character&gt;' '\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&lt;the_field_separator_character&gt; -f&lt;comma-separated_list_of_columns&gt; input_file | v.in.ascii in=- &lt;your_options&gt;
</pre></div>


<h2>EXAMPLES</h2>

<h3>Example 1a) - standard format mode</h3>
Sample ASCII polygon vector map for 'standard' format mode. 
The two areas will be assigned categories 20 and 21. 
<p><div class="code"><pre>
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
</pre></div>

<h3>Example 1b) - standard format mode</h3>

Sample ASCII 3D line vector map for 'standard' format mode with simplified input
(note the space field separator).
Note the <b>-z</b> flag indicating 3D vector input, and the <b>-n</b> flag
indicating no vector header should be expected from the input file.

<div class="code"><pre>
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
</pre></div>

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).

<h3>Example 2 - point format mode</h3>

Generate a 2D points vector map 'coords.txt' as ASCII file:
<div class="code"><pre>
1664619|5103481
1664473|5095782
1664273|5101919
1663427|5105234
1663709|5102614
</pre></div>

<p>Import into GRASS:
<div class="code"><pre>
v.in.ascii input=coords.txt output=mymap
</pre></div>
As the <b>cat</b> option is set to 0 by default, an extra column 'cat'
containing the category numbers will be auto-generated.

<h3>Example 3 - point format mode</h3>

Generate a 2D points vector map 'points.dat' as ASCII file:
<div class="code"><pre>
1|1664619|5103481|studna
2|1664473|5095782|kadibudka
3|1664273|5101919|hruska
4|1663427|5105234|mysi dira
5|1663709|5102614|mineralni pramen
</pre></div>

<p>Import into GRASS:
<div class="code"><pre>
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)'
</pre></div>

<p>The module is reading from standard input, using the default '|' (pipe) delimiter.

<h3>Example 4 - point format mode - CSV table</h3>

Import of a 3D points CSV table ('points3d.csv') with attributes:
<div class="code"><pre>
"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
</pre></div>
<p>Import into GRASS:
<div class="code"><pre>
# 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
</pre></div>

<h3>Example 5 - point format mode</h3>

Generating a 3D points vector map from DBMS (idcol must be an integer column):<br>
<div class="code"><pre>
echo "select east,north,elev,idcol from mytable" | db.select -c | v.in.ascii in=- -z out=mymap
</pre></div>

With <b>in=-</b>, the module is reading from standard input, using the default '|' (pipe) delimiter.
<br>
The import works for 2D maps as well (no elev column and no '-z' flag).


<h3>Example 6 - point format mode</h3>

Generate a 3D points vector map 'points3d.dat' with attributes as ASCII file:
<div class="code"><pre>
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
</pre></div>
<p>Import into GRASS:
<div class="code"><pre>
#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
</pre></div>


<h3>Example 7 - point format mode</h3>

Generate points file by clicking onto the map:
<div class="code"><pre>
#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)'
</pre></div>

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 <em>v.in.ascii</em>, only the vector map geometry will be generated.

<h3>Example 8 - point format mode</h3>

Convert ground control points into vector points:
<div class="code"><pre>
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'
</pre></div>

<h2>REFERENCES</h2>

<a href="sql.html">SQL command notes</a> for creating databases
<br>
<a href="vectorascii.html">GRASS ASCII vector format</a> specification

<h2>SEE ALSO</h2>

<em>
<a href="db.execute.html">db.execute</a>,
<a href="r.in.ascii.html">r.in.ascii</a>,
<a href="r.in.xyz.html">r.in.xyz</a>,
<a href="v.build.html">v.build</a>,
<a href="v.build.polylines.html">v.build.polylines</a>,
<a href="v.centroids.html">v.centroids</a>,
<a href="v.clean.html">v.clean</a>,
<a href="v.db.connect.html">v.db.connect</a>,
<a href="v.import.html">v.import</a>,
<a href="v.info.html">v.info</a>,
<a href="v.out.ascii.html">v.out.ascii</a>
</em>

<h2>AUTHORS</h2>

Michael Higgins,
U.S.Army Construction Engineering 
Research Laboratory<br>
James Westervelt, U.S.Army Construction Engineering 
Research Laboratory<br>
Radim Blazek, ITC-Irst, Trento, Italy

<p><i>Last changed: $Date$</i>