v.lrs.segment - GRASS GIS manual
Author: GRASS Development Team
Description: v.lrs.segment: Creates points/segments from input lines, linear reference system and positions read from stdin or a file.
Keywords: vector, linear reference system, network

## NAME

v.lrs.segment - Creates points/segments from input lines, linear reference system and positions read from stdin or a file.

## KEYWORDS

vector, linear reference system, network

## SYNOPSIS

v.lrs.segment
v.lrs.segment --help
v.lrs.segment input=name output=name [llayer=string] [rsdriver=string] [rsdatabase=string] rstable=string [file=name] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

### Flags:

--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 vector map
  Input vector map containing lines
output=name [required]
  Output vector map where segments will be written
llayer=string
  Layer number or name
  Line layer
  Default: 1
rsdriver=string
  Driver name for reference system table
  Options: dbf, ogr, pg, sqlite
  Default: sqlite
rsdatabase=string
  Database name for reference system table
  Default: $GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db
rstable=string [required]
  Name of the reference system table
file=name
  Name of file containing segment rules. If not given, read from stdin.

## DESCRIPTION

v.lrs.segment creates points/segments from input lines, linear reference system and positions read from `standard in` or a file.

The format is as follows:

    P <point_id> <line_id> <milepost>+<offset> [<side offset>]
    L <segment_id> <line_id> <milepost>+<offset> <milepost>+<offset> [<side offset>]

## NOTES

For more information and examples see the help page for v.lrs.segment's sister module, v.segment.

## EXAMPLE

This example is written for the Spearfish dataset (it continues the example from v.lrs.create).

In this example, the 'route_lrs' shall be extended for a new position (point) along the LRS after bus stop 4:

    # new point on LRS
    echo "P 7 22 4+180" | v.lrs.segment route_lrs out=route_lrs_new rstable=route_lrs

    g.region vector=route_lrs n=n+100 s=s-100 -p
    d.erase
    # existing LRS
    d.vect route_lrs
    d.vect busstops disp=attr attr=cat size=10 bg=white lcol=blue yref=bottom
    d.vect busstops icon=basic/circle fcol=blue
    db.select table=route_lrs

    # show modified map
    d.vect route_lrs_new col=red

## TODO

Figure out how to merge result into existing LRS map and table.

## SEE ALSO

LRS tutorial,
Introducing the Linear Reference System in GRASS,
v.lrs.create, v.lrs.where, v.lrs.label, v.segment

## AUTHOR

Radim Blazek

## SOURCE CODE

Available at: v.lrs.segment source code (history)

Accessed: Thursday Jun 04 03:31:24 2026

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