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v.net.steiner: Create Steiner tree for the network and given terminals Note that 'Minimum Steiner Tree' problem is NP-hard and


v.net.steiner - Create Steiner tree for the network and given terminals Note that 'Minimum Steiner Tree' problem is NP-hard and heuristic algorithm is used in this module so the result may be sub optimal


vector, networking


v.net.steiner v.net.steiner help v.net.steiner [-g] input=name output=name [type=string[,string,...]] [alayer=integer] [nlayer=integer] [acolumn=string] tcats=range [nsp=integer] [--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 terminals) Default: 2 acolumn=string Arcs' cost column (for both directions) tcats=range Category values Categories of points on terminals (layer is specified by nlayer) nsp=integer Number of steiner points (-1 for all possible) Default: -1


v.net.steiner calculates the optimal connection of nodes on a vector network. A Steiner tree is used to calculate the minimum-cost vector network connecting some number of end nodes in a network framework. For example it could be used to find the path following a road system which will minimize the amount of fibre optic cable needed to connect a series of satellite offices.
Steiner tree for for 6 digitized nodes (Spearfish): g.copy vect=roads,myroads v.db.addcol myroads col="cost double precision" # define traveling costs as inverse of speed limit: v.db.update myroads col=cost val=1/50 v.db.update myroads col=cost val=1/75 where="label='interstate'" v.db.update myroads col=cost val=1/5 where="label='unimproved road'" v.db.update myroads col=cost val=1/25 where="label='light-duty road, improved surface'" v.db.select myroads # we have 6 locations to allocate 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 cat=1 x=2 y=3 out=centers col="cat integer, \ east double precision, north double precision, label varchar(43)" 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 # The network is now prepared. g.region vect=myroads_net d.mon x0 d.vect myroads_net d.vect -c centers icon=basic/triangle d.font verdana d.vect centers col=red disp=attr attrcol=label lsize=12 v.net.steiner myroads_net acol=cost tcats=1-6 out=mysteiner d.vect mysteiner col=blue width=2
d.path, v.net, v.net.alloc, v.net.iso, v.net.path, v.net.salesman


Radim Blazek, ITC-Irst, Trento, Italy Documentation: Markus Neteler Last changed: $Date: 2007-11-12 05:28:29 +0100 (Mon, 12 Nov 2007) $ Full index (C) 2003-2010 GRASS Development Team V.NET.STEINER(1)

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