NAME

v.net.path - Find shortest path on vector network. Reads start/end pointsfrom standard input in format: start_point_category end_point_category Points must be exactly on network nodes.

SYNOPSIS

v.net.path
v.net.path help
v.net.path [-g] input=string output=string [type=string[,string,...]] [afield=integer] [nfield=integer] [afcol=string] [abcol=string] [ncol=string]

Flags:

-g
Use geodesic calculation for longitude-latitude locations

Parameters:

input=string
Name of input vector
output=string
Name of output vector
type=string
Arc type
Options: line,boundary
Default: line,boundary
afield=integer
Arc field
Default: 1
nfield=integer
Node field
Default: 2
afcol=string
Arc forward/both direction(s) cost column
abcol=string
Arc backward direction cost column
ncol=string
Node cost column

DESCRIPTION

v.net.path can find shortest path(s) on the vector network. Costs may be either line lengths, or attributes saved in a database table. These attributes values are taken as costs of whole segments. If read from the table, arcs' costs may be different in both directions. Shortest paths are written to output vector file and attached attribute table.

NOTE

If the columns 'afcol', 'abcol' and 'ncol' costs are not specified, the length of network segments is measured and zero costs are assumed for nodes.

When using attributes, the length of segments is not used. To get more precise results, length should be taken indirectly into account by attributes. For example, to get the fastest path the columns 'max_speed' and 'length' are required. The correct fastest path can then be found by specifying afcol=length/max_speed (pg driver). If needed, the line length can be calculated and written to the attributes table by v.to.db.

SEE ALSO

d.path, v.net, v.net.alloc, v.net.iso, v.net.salesman, v.net.steiner, v.to.db

AUTHOR

Radim Blazek, ITC-Irst, Trento, Italy

Last changed: $Date: 2004/03/09 08:29:38 $


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