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

<h2>DESCRIPTION</h2>

<em>v.in.ascii</em> converts a vector map in ASCII format 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>
The <a HREF="v.out.ascii.html">v.out.ascii</a> GRASS module performs
the function of <em>v.in.ascii</em> in reverse; i.e., it converts
vector maps in binary format to ASCII 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>
Latitude/Longitude data may be given in a number of ways.
Decimal degrees must be positive or negative instead of using a hemisphere
letter. Mixed coordinates must use a hemisphere letter. Whole minutes and
seconds must always contain two digits (example: use <tt>167:03:04.567</tt>;
and not <tt>167:3:4.567</tt>). 
<br><br>
Acceptable formats:<br>
<i>key: D=Degrees; M=Minutes; S=Seconds; h=Hemisphere (N,S,E,W)</i>
<ul>
  <li><tt>(+/-)DDD.DDDDD</tt>
  <li><tt>DDDh</tt>
  <li><tt>DDD:MMh</tt>
  <li><tt>DDD:MM.MMMMMh</tt>
  <li><tt>DDD:MM:SSh</tt>
  <li><tt>DDD:MM:SS.SSSSSh</tt>
</ul>

<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
(creating a GRASS vector level 1 vector map) 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 recommened 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 the to
disabling of topology.

<p>
A GRASS ASCII vector map (in <b>standard format</b> mode) may contain a mix
of primitives including points, lines, boundaries, centroids, areas,
faces, and kernels.
<!--This format is described in the
<a HREF="http://freegis.org/cgi-bin/viewcvs.cgi/~checkout~/grass6/doc/vector/vector.html#ascii">GRASS
Vector ASCII Format Specification</a>.--> The GRASS ASCII vector format
may contain a header with various metadata (see example below). 
The header is not required if the <b>-n</b> flag is used.

<p>The header is similar as the head file of vector binary format but
contains bounding box also. Key words are:

<pre>
ORGANIZATION
DIGIT DATE
DIGIT NAME
MAP NAME
MAP DATE
MAP SCALE
OTHER INFO
ZONE
WEST EDGE
EAST EDGE
SOUTH EDGE
NORTH EDGE
MAP THRESH
</pre>

<p>The body begins with the row:

<pre>
VERTI:
</pre>

followed by records of primitives:

<pre>
TYPE NUMBER_OF_COORDINATES [NUMBER_OF_CATEGORIES]
 X Y [Z]
....
 X Y [Z]
[ LAYER CATEGORY]
....
[ LAYER CATEGORY]
</pre>

Everything above in <tt>[&nbsp;]</tt> is optional. 

<p>
The primitive codes are as follows:
<ul>
<li>'P': point</li>
<li>'L': line</li>
<li>'B': boundary</li>
<li>'C': centroid</li>
<li>'F': face (3D boundary)</li>
<li>'K': kernel (3D centroid)</li>
<li>'A': area (boundary) - better use 'B'; kept only for backward compatibility</li>
</ul>

The coordinates are listed following the initial line containing the
primitive code, the total number of vectors in the series, and (optionally)
the number of categories (1 for a single layer, higher for multiple layers).
Below that 1 or several lines follow to indicate the layer number and
the category number (ID).
<br>
The order of coordinates is
<div class="code"><pre>
  X Y [Z]
</pre></div>

In pre-GRASS 6 versions of the ASCII file, the order of coordinates is:
<div class="code"><pre>
Y X
</pre></div>

If old version is requested, the <b>output</b> files from <em>v.out.ascii</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 ID column</h3>

If the input file does not contain a vector ID 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>fs=','</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 <tt>points</tt> 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 varchars(), not as numbers.
A warning will be issued which can be ignored.

<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
# do not use the input= option
cut -d&lt;the_field_separator_character&gt; -f&lt;comma-separated_list_of_columns&gt; input_file | v.in.ascii &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. 
The example can be tested in the Spearfish sample dataset:
<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 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 <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.
The example can be tested in the Spearfish sample dataset:

<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 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</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 IDs will be auto-generated.

<h3>Example 3</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 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</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 -z out=mymap
</pre></div>

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 5</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|closet
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 -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 6</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 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 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 7</h3>

Convert ground control points from i.points into vector points:
<div class="code"><pre>
cat $MAPSET/group/$GROUP/POINTS | v.in.ascii out=$GROUP_gcp fs=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

<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.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>