Re: number of Trangles in a graph-network
- To: mathgroup at smc.vnet.net
- Subject: [mg99376] Re: number of Trangles in a graph-network
- From: dh <dh at metrohm.com>
- Date: Mon, 4 May 2009 06:00:51 -0400 (EDT)
- References: <gtefaf$197$1@smc.vnet.net>
Hi Luca,
try e.g.:
=======================
Needs["Combinatorica`"];
Needs["GraphUtilities`"]
g = RandomGraph[7, 0.5];
ShowGraph[g, VertexNumber -> True]
ad = AdjacencyMatrix[g] // Normal;
triangles = {};
Do[ (*loop over first point*)
t = ad[[i, i + 1 ;; -1]];(*take upper half*)
t = i + Position[t, 1] // Flatten;
t = Subsets[t, {2}];(*possible 2. and 3. point*)
t = Select[t,
ad[[Sequence @@ #]] == 1 &];(*check if 2. and 3. point connected*)
t = Prepend[#, i] & /@ t;
triangles = Join[triangles, t];
, {i, 1, Length[ad]}];
triangles
======================
Daniel
Luca Cinacchio wrote:
> Greetings,
>
> having a graph (network, i.e. one created with RandomGraph) wich can have
> not connected nodes, I would like to count the total number of triangles
> inside the graph.
> I gave a look to Combinatorica and its related book by Pemmaraju Skiena,
> but I did'nt find any solution (maybe I am wrong). Do you know if there is
> a easy way to answer this problem with Mathematica and/or Combinatorica?
> Thanks in advance.
>