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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  [-g] input=name output=name  [type=string[,string,...]]
       [alayer=integer]    [nlayer=integer]    [acolumn=string]    ccats=range
       [--overwrite]  [--verbose]  [--quiet]

   Flags:
       -g
           Use geodesic calculation for longitude-latitude locations

       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=name
           Name of input vector map

       output=name
           Name for output vector map

       type=string[,string,...]
           Arc type
           Options: line,boundary
           Default: line,boundary

       alayer=integer
           Layer number
           Arc layer
           Default: 1

       nlayer=integer
           Layer number
           Node layer (used for cities)
           Default: 2

       acolumn=string
           Arcs' cost column (for both directions)

       ccats=range
           Category values
           Categories  of  points  ('cities')  on nodes (layer is specified by
           nlayer)

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.

NOTES

       Arcs can be closed using cost = -1.

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 ccats=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"
       # 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:
       v.db.update myroads_net_time layer=3 col=cost val="length / speed * 60"
       # find the fastest path
       v.net.salesman  myroads_net_time  alayer=3 nlayer=2 acol=cost ccats=1-6
       out=mysalesman_time
        To display the result, run for example:
       # Display the results
       g.region vect=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
       Documentation: Markus Neteler, Markus Metz

       Last changed: $Date: 2013-05-23 13:01:55 -0700 (Thu, 23 May 2013) $

       Full index

       © 2003-2013 GRASS Development Team



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