## DESCRIPTION

v.in.ascii converts a vector map in ASCII format to a vector 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.

The v.out.ascii GRASS module performs the function of v.in.ascii 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.

## 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 columns. The attribute column will be auto-scanned for type, but may be explicitly declared along with the geometry columns using the columns parameter.

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 `167:03:04.567`; and not `167:3:4.567`).
Acceptable formats:
key: D=Degrees; M=Minutes; S=Seconds; h=Hemisphere (N,S,E,W)

- `(+/-)DDD.DDDDD`
- `DDDh`
- `DDD:MMh`
- `DDD:MM.MMMMMh`
- `DDD:MM:SSh`
- `DDD:MM:SS.SSSSSh`

  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 (creating a GRASS vector level 1 vector map) 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 subregion (the -r flag) before resorting to the disabling of topology.

  A GRASS ASCII vector map (in standard format mode) may contain a mix of primitives including points, lines, boundaries, centroids, areas, faces, and kernels. The GRASS ASCII vector format may contain a header with various metadata (see example below). The header is not required if the -n flag is used.

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

      ORGANIZATION
      DIGIT DATE
      DIGIT NAME
      MAP NAME
      MAP DATE
      MAP SCALE
      OTHER INFO
      ZONE
      WEST EDGE
      EAST EDGE
      SOUTH EDGE
      NORTH EDGE
      MAP THRESH

  The body begins with the row:

      VERTI:

  followed by records of primitives:

      TYPE NUMBER_OF_COORDINATES [NUMBER_OF_CATEGORIES]
       X Y [Z]
      ....
       X Y [Z]
      [ LAYER CATEGORY]
      ....
      [ LAYER CATEGORY]

  Everything above in `[ ]` is optional.

  The primitive codes are as follows:

  - 'P': point
  - 'L': line
  - 'B': boundary
  - 'C': centroid
  - 'F': face (3D boundary)
  - 'K': kernel (3D centroid)
  - 'A': area (boundary) - better use 'B'; kept only for backward compatibility
  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).
  The order of coordinates is

        X Y [Z]

  In pre-GRASS 6 versions of the ASCII file, the order of coordinates is:

      Y X

  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.

  ### Import of files without category ID column

  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 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 fs=',' option with v.in.ascii in points mode. If the input file contains any header lines, such as column 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 located 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 varchars(), not as numbers. A warning will be issued which can be ignored.

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

      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

  ### Example 1b) - standard format mode

  Sample ASCII 3D line vector map for 'standard' format mode with simplified input (note the space field separator). Note the -z flag indicating 3D vector input, and the -n flag indicating no vector header should be expected from the input file. The example can be tested in the Spearfish sample dataset:

      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

  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' containing the IDs 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 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

  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 -z out=mymap

  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 5 - 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|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

  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 -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 6 - 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 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)'

  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 7 - point format mode

  Convert ground control points from i.points into vector points:

      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'

  ## REFERENCES

  SQL command notes for creating databases

  ## SEE ALSO

  db.execute, r.in.ascii, r.in.xyz, v.build, v.build.polylines, v.centroids, v.clean, v.db.connect, v.info, 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

  Last changed: $Date: 2013-05-03 12:47:09 -0700 (Fri, 03 May 2013) $