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) $

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