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MathGroup Archive 2005

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Re: Directed Graph from Adjacency Matrix

  • To: mathgroup at smc.vnet.net
  • Subject: [mg58805] Re: [mg58783] Directed Graph from Adjacency Matrix
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Tue, 19 Jul 2005 04:10:14 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200507180721.DAA23417@smc.vnet.net>
  • Reply-to: murray at math.umass.edu
  • Sender: owner-wri-mathgroup at wolfram.com

    Needs["DiscreteMath`Combinatorica`"]

    a = {{0, 1, 0}, {0, 0, 1}, {1, 0, 0}};
    FromAdjacencyMatrix[a, Type -> Directed]
â??Graph:<6, 3, Directed>â??
    ShowGraph[%]
(* output shows a directed cycle on 3 vertices *)

However:

    mat = ToAdjacencyMatrix[Cycle[3, Directed -> True]]
{{0, 1, 1}, {1, 0, 1}, {1, 1, 0}}

    g = FromAdjacencyMatrix[mat, Type -> Directed]
â??Graph:<6, 3, Directed>â??
   ShowGraph[g]
(* the complete directed graph on 3 vertices with each edgedirected both 
ways *)


In view of the preceding, you may want to use adjacency lists, rather 
than the adjacency matrix, for directed graphs.


confused wrote:
> I am new to Mathematica.  Here is my question.  How would I get a 
> directed graph from an adjacency matrix?  For instance, the 3x3 matrix 
> {{0,1,0},{0,0,1},{1,0,0}} defines a directed 3-cycle, but when I try to 
> turn it into a graph using FromAdjacencyMatrix, Mathematica returns a 
> graph with only two edges.
> 
> Thank you.
> 
> 

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305



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