## NAME

d.what.vect - Allows the user to interactively query the category contents of a (binary) vector map layer at user-selected locations within the current geographic region.
(GRASS Display Program)

## SYNOPSIS

d.what.vect
d.what.vect help
d.what.vect [-1t] map=name [table=name] [key=name]

## DESCRIPTION

d.what.vect outputs the category value(s) associated with user-specified location(s) in a user-specified vector map layer. This program currently returns only category values for line types in the user-specified vector file.

The program will query the contents of the vector map layer named by the user on the command line. This map layer must exist in the user's current mapset search path.

The program activates the mouse, and expects the user to indicate the location(s) to be queried by depressing a mouse button over desired location(s) within the current geographic region in the active display frame on the graphic monitor.

Alternatively user can specify table= and key= and window with database attributes will be opened for each selected object with assigned category.

### Flag:

-1
  Identify and query just one point location. Only one mouse click is executed. This option is provided for shell scripts and programs that want to obtain only one point from the user.
-t
  Provide only terse output. This option is provided to simplify the parsing of output by other programs. Database connection must be set up by db.connect first.

### Parameter:

map=name
  Name of an existing binary vector map in the user's mapset search path.
table=name
  Name of database table containing attributes.
key=name
  Name of database table key (id) column.

## EXAMPLE

A sample d.what.vect session is given below. Although it is not necessary that the user first display a vector map to be queried in the active display frame, it is helpful to have a map displayed there for reference.

  d.vect map=roads.24000
  Displays the 1:24,000 scale roads vector map layer on the graphics monitor.

  d.what.vect map=roads.24000
  After typing this, the user moves the mouse to a desired location on the displayed roads map layer, and presses the left mouse button to query the category value of the roads vector map at this location. The program then outputs the category value of a line type corresponding to this user-selected map location, for the vector map queried by the user.

  The query may be repeated as often as desired using the left mouse button. The right button on the mouse is used to quit the d.what.vect session.

  Users can also use this program inside of shell scripts that require as input a map category value and a mouse button depressed. Users can set the -1 flag to run d.what.vect only once, and return only the map category value found and the number of the mouse button depressed. (Mouse button return values are as follows: 0 indicates no button was pressed, 1 indicates that the left mouse button was pressed, 2 indicates the middle button was pressed, and 3 indicates that the right mouse button was pressed.)

  ## NOTES

  Currently, d.what.vect only outputs category values for lines. It does not output category labels for lines, nor output category values or category labels for areas in a vector file.

  d.what.vect will always print its output to the user's terminal screen. d.what.vect output can be redirected into a file; however, if it is, the output will go both to the screen and to the file. For example:

    d.what.vect map=roads > what.out
  will both send d.what.vect output to the screen and capture its output in the file named what.out.

  d.what.rast can be used to interactively query the map category contents of multiple raster map layers at user-selected locations.

  ## SEE ALSO

  d.rast
  d.vect
  d.what.rast
  g.region
  db.connect
  parser

  ## AUTHOR

  Jim Hinthorne, Central Washington University
  Upgrades: Dennis Finch, National Park Service