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NAME

       v.net.salesman  - Creates a cycle connecting given nodes (Traveling salesman problem).
       Note that TSP is NP-hard, heuristic algorithm is used by this module and created cycle may
       be sub optimal

KEYWORDS

       vector, network, salesman

SYNOPSIS

       v.net.salesman
       v.net.salesman --help
       v.net.salesman   [-tg]   input=name   output=name    center_cats=range    arc_layer=string
       arc_type=string[,string,...]             node_layer=string             [arc_column=string]
       [arc_backward_column=string]          [turn_layer=string]          [turn_cat_layer=string]
       [sequence=name]   [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       -t
           Use turntable

       -g
           Use geodesic calculation for longitude-latitude locations

       --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
           Or data source for direct OGR access

       output=name [required]
           Name for output vector map

       center_cats=range [required]
           Category values
           Categories of points (’cities’) on nodes (layer is specified by nlayer)

       arc_layer=string [required]
           Arc layer
           Vector  features  can have category values in different layers. This number determines
           which layer to use. When used with direct OGR access this is the layer name.
           Default: 1

       arc_type=string[,string,...] [required]
           Arc type
           Input feature type
           Options: line, boundary
           Default: line,boundary

       node_layer=string [required]
           Node layer (used for cities)
           Vector features can have category values in different layers. This  number  determines
           which layer to use. When used with direct OGR access this is the layer name.
           Default: 2

       arc_column=string
           Arc forward/both direction(s) cost column (number)

       arc_backward_column=string
           EXPERIMENTAL: Arc backward direction cost column (number)

       turn_layer=string
           Layer with turntable
           Relevant only with -t flag
           Default: 3

       turn_cat_layer=string
           Layer with unique categories used in turntable
           Relevant only with -t flag
           Default: 4

       sequence=name
           Name for output file holding node sequence ("-" for stdout)

DESCRIPTION

       v.net.salesman calculates the optimal route to visit nodes on a vector network.

       Costs may be either line lengths, or attributes saved in a database table. These attribute
       values are taken as costs of whole segments, not as costs to traverse a length unit  (e.g.
       meter)  of  the  segment.   For  example,  if  the  speed limit is 100 km / h, the cost to
       traverse a 10 km long road segment must be calculated as
       length / speed = 10 km / (100 km/h) = 0.1 h.
       Supported are cost assignments for arcs, and also different costs for both directions of a
       vector line.  For areas, costs will be calculated along boundary lines.

       The  input  vector  needs  to be prepared with v.net operation=connect in order to connect
       points representing center nodes to the network.

       Points specified by category must be exactly on network nodes, and the  input  vector  map
       needs to be prepared with v.net operation=connect.

       Application  of  flag  -t  enables  a  turntable  support.   This flag requires additional
       parameters turn_layer and turn_cat_layer that are otherwise ignored.  The turntable allows
       to model e.g. traffic code, where some turns may be prohibited.  This means that the input
       layer is expanded by turntable with costs of every possible  turn  on  any  possible  node
       (intersection)  in  both  directions.   Turntable can be created by the v.net module.  For
       more information about turns in the vector network analyses see wiki page.

NOTES

       Arcs can be closed using cost = -1.  Turns support: The costs of turns on  visiting  nodes
       are not taken in account.

EXAMPLE

       Traveling salesman for 6 digitized nodes (Spearfish):

       Shortest path, along unimproved roads:

       Fastest path, along highways:

       Searching  for  the shortest path using distance and the fastest path using traveling time
       according to the speed limits of different road types:
       # Spearfish
       g.copy vect=roads,myroads
       # we have 6 locations to visit on our trip
       echo "1|601653.5|4922869.2|a
       2|608284|4923776.6|b
       3|601845|4914981.9|c
       4|596270|4917456.3|d
       5|593330.8|4924096.6|e
       6|598005.5|4921439.2|f" | v.in.ascii in=- cat=1 x=2 y=3 out=centers col="cat integer, \
                                east double precision, north double precision, label varchar(43)"
       # verify data preparation
       v.db.select centers
       v.category centers op=report
       # type       count        min        max
       # point          6          1          6
       # create lines map connecting points to network (on layer 2)
       v.net myroads points=centers out=myroads_net op=connect thresh=500
       v.category myroads_net op=report
       # Layer / table: 1 / myroads_net
       # type       count        min        max
       # line         837          1          5
       #
       # Layer: 2
       # type       count        min        max
       # point          6          1          5
       # find the shortest path
       v.net.salesman myroads_net center_cats=1-6 out=mysalesman_distance
       # set up costs as traveling time
       # create unique categories for each road in layer 3
       v.category in=myroads_net out=myroads_net_time opt=add cat=1 layer=3 type=line
       # add new table for layer 3
       v.db.addtable myroads_net_time layer=3 col="cat integer,label varchar(43),length double precision,speed double precision,cost double precision,bcost double precision"
       # copy road type to layer 3
       v.to.db myroads_net_time layer=3 qlayer=1 opt=query qcolumn=label columns=label
       # upload road length in miles
       v.to.db myroads_net_time layer=3 type=line option=length col=length unit=miles
       # set speed limits in miles / hour
       v.db.update myroads_net_time layer=3 col=speed val="5.0"
       v.db.update myroads_net_time layer=3 col=speed val="75.0" where="label=’interstate’"
       v.db.update myroads_net_time layer=3 col=speed val="75.0" where="label=’primary highway, hard surface’"
       v.db.update myroads_net_time layer=3 col=speed val="50.0" where="label=’secondary highway, hard surface’"
       v.db.update myroads_net_time layer=3 col=speed val="25.0" where="label=’light-duty road, improved surface’"
       v.db.update myroads_net_time layer=3 col=speed val="5.0" where="label=’unimproved road’"
       # define traveling costs as traveling time in minutes:
       # set forward costs
       v.db.update myroads_net_time layer=3 col=cost val="length / speed * 60"
       # set backward costs
       v.db.update myroads_net_time layer=3 col=bcost val="length / speed * 60"
       # find the fastest path
       v.net.salesman myroads_net_time arc_layer=3 node_layer=2 arc_column=cost arc_backward_column=bcost center_cats=1-6 out=mysalesman_time
       To display the result, run for example:
       # Display the results
       g.region vector=myroads_net
       # shortest path
       d.mon x0
       d.vect myroads_net
       d.vect centers -c icon=basic/triangle
       d.vect mysalesman_distance col=green width=2
       d.font Vera
       d.vect centers col=red disp=attr attrcol=label lsize=12
       # fastest path
       d.mon x1
       d.vect myroads_net
       d.vect centers -c icon=basic/triangle
       d.vect mysalesman_time col=green width=2
       d.font Vera
       d.vect centers col=red disp=attr attrcol=label lsize=12

SEE ALSO

       d.path, v.net, v.net.alloc, v.net.iso, v.net.path, v.net.steiner

AUTHOR

       Radim Blazek, ITC-Irst, Trento, Italy
       Markus Metz
       Documentation: Markus Neteler, Markus Metz

   TURNS SUPPORT
       The turns support was implemnented as part of  GRASS  GIS  turns  cost  project  at  Czech
       Technical  University  in  Prague,  Czech Republic.  Eliska Kyzlikova, Stepan Turek, Lukas
       Bocan and Viera  Bejdova  participated  at  the  project.   Implementation:  Stepan  Turek
       Documentation: Lukas Bocan Mentor: Martin Landa

       Last changed: $Date: 2016-11-14 00:05:32 +0100 (Mon, 14 Nov 2016) $

SOURCE CODE

       Available at: v.net.salesman source code (history)

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