Re: GraphPath With Edge Weights

*To*: mathgroup at smc.vnet.net*Subject*: [mg126665] Re: GraphPath With Edge Weights*From*: Ralph Dratman <ralph.dratman at gmail.com>*Date*: Wed, 30 May 2012 04:08:19 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201205290945.FAA06632@smc.vnet.net>

Dana, do you mean, you hope Wolfram consolidates the graph-handling routines? If so, I sure agree. Many routines don't seem to work properly, and bringing in Combinatorica has been catastrophic every time I've tried it. Ralph On Tue, May 29, 2012 at 5:45 AM, Dana DeLouis <dana01 at me.com> wrote: > = = = = = = = = = = > I hope they consolidate Graphics in the next release > HTH :>) > Dana DeLouis > Mac & Math 8 > = = = = = = = = = = >> . . if I compute GraphPath[graph, 1, 3] it returns >> the unweighted shortest path {1, 3}. > > My opinion is that graphics are so confusing now with multiple overlaps between packages, Combinatorica, and new built in functions in version 8. > > The use of WeightedAdjacencyMatrix appears to solve this problem. > Not sure if it's the best solution. > > Needs["GraphUtilities`"] > > graph=Graph[{UndirectedEdge[1,2],UndirectedEdge[2,3],UndirectedEdge[3,1]},EdgeWeight->{1,2,9}]; > > GraphDistance[graph,1,3] > 3. > > GraphPath[graph,1,3] > {1,3} > > // Workaround: > > GraphPath[WeightedAdjacencyMatrix[graph],1,3] > {1,2,3} > > Here is a slightly larger graph (4 points) > > // Setup: > > g=CompleteGraph[4]; > wgts = Thread[EdgeList[g]->Range[EdgeCount[g]]]; > > // Graph > > g=CompleteGraph[4, > Rule[VertexShapeFunction,List["Name"]], > EdgeWeight->wgts, > EdgeLabels->wgts, > ImagePadding->10, > EdgeLabelStyle->Directive[Blue,Italic,20] > ] > > GraphDistance[g,2,4] > 4. > > GraphPath[WeightedAdjacencyMatrix[g],2,4] > {2,1,4} > > GraphPath[WeightedAdjacencyMatrix[g],2,3] > {2,1,3} > > GraphPath[WeightedAdjacencyMatrix[g],3,4] > {3,1,4} > > = = = = = = = = = = > I hope they consolidate Graphics in the next release > HTH :>) > Dana DeLouis > Mac & Math 8 > = = = = = = = = = = > > > > > On May 28, 5:14 am, Ben <ben... at gmail.com> wrote: >> I can't figure out how to compute a shortest path using GraphPath with >> edge weights. I first define a graph as follows. >> >> graph = Graph[{UndirectedEdge[1,2], UndirectedEdge[2,3], >> UndirectedEdge[3,1]}, EdgeWeight->{1, 2, 9}] >> >> After loading GraphUtilities I compute GraphDistance[graph, 1, 3] and >> it correctly returns the shortest path distance of 3 corresponding to >> the path {1, 2, 3}. But if I compute GraphPath[graph, 1, 3] it >> returns the unweighted shortest path {1, 3}. Even if I use >> GraphPath[graph, 1, 3, Weighted->True] it still returns the same >> answer of {1, 3}. (Weighted is supposed be True by default anyway.) >> What am I doing wrong? >> >> Thanks. > > >

**References**:**Re: GraphPath With Edge Weights***From:*Dana DeLouis <dana01@me.com>