Re: plotting weighted graphs

*To*: mathgroup at smc.vnet.net*Subject*: [mg55382] Re: plotting weighted graphs*From*: bghiggins at ucdavis.edu*Date*: Mon, 21 Mar 2005 03:01:48 -0500 (EST)*References*: <d1ecqp$euc$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Erik, It is much easier to add edge weights using the combinatorica package. I have a notebook that illustrates the procedure that I can send you if that would help. You can also do it with GraphPlot but it is more difficult. Here is how I did it: << DiscreteMath`GraphPlot`; myAdjMat = {{0, 1, 1, 0, 1, 1}, {1, 0, 1, 1, 0, 1}, {1, 1, 0, 1, 1, 0}, {0, 1, 1, 0, 1, 1}, {1, 0, 1, 1, 0, 1}, {1, 1, 0, 1, 1, 0}}; We will need some auxillary functions. First a function that defines the weight for a given edge. I am asumming the adjacency matrix is symmetric (non directed graph) switchFunc[i_, j_] := Switch[{i, j}, {2, 1}, "A", {3, 1}, "B", {5, 1}, "C", {6, 1}, "D", {3, 2}, "E", {4, 2}, "F", { 6, 2}, "G", {4, 3}, "H", {5, 3}, "I", {5, 4}, "J", {6, 4}, "K ", {6, 5}, "L", _, ""] I will also need the coordinates for the vertices: coord = GraphCoordinates[myAdjMat] Then we define an edgelabel function that returns a graphic primitive. The arguments for this function are the edge variables, edgelabel2[i_, j_] := Text[switchFunc[i, j], (coord[[i]] + coord[[j]])/2] Then we define the edge style function esf[i_, j_] := Block[{}, {{Blue, Line[{i, j}]}, {Red, edgelabel2[i, j]}}] and finally we plot the graph GraphPlot[myAdjMat, EdgeStyleFunction -> esf] Hope this helps, Cheers, Brian Erik Itter wrote: > Hi, I have a hopefully quite easy question: > how do you plot graphs with weighted edges? > > I have the matrix specified by its adjadcency matrix using different numbers as weights, works so > far. Now I would like to plot the matrix numbering the vertices from 1 to n and label the edges with > their weights. Its 5.1 therefore I think I could use GraphPlot (which draws the graph with no > labeling at all at the moment [but colors depending on weights]) if I knew the proper > EdgeStyleFunction and VertexStyleFunction. > > > > All suggestions welcome.