[R] Clustering algorithms don't find obvious clusters

[Dave Roberts]

Henrik,

     The clustering algorithms you refer to (and almost all others) 
expect the matrix to be symmetric.  They do not seek a graph-theoretic 
solution, but rather proximity in geometric or topological space.

     How did you convert y9oru matrix to a dissimilarity?

Dave Roberts

Henrik Aldberg wrote:
> I have a directed graph which is represented as a matrix on the form
> 
> 
> 0 4 0 1
> 
> 6 0 0 0
> 
> 0 1 0 5
> 
> 0 0 4 0
> 
> 
> Each row correspond to an author (A, B, C, D) and the values says how many
> times this author have cited the other authors. Hence the first row says
> that author A have cited author B four times and author D one time. Thus the
> matrix represents two groups of authors: (A,B) and (C,D) who cites each
> other. But there is also a weak link between the groups. In reality this
> matrix is much bigger and very sparce but it still consists of distinct
> groups of authors.
> 
> 
> My problem is that when I cluster the matrix using pam, clara or agnes the
> algorithms does not find the obvious clusters. I have tried to turn it into
> a dissimilarity matrix before clustering but that did not help either.
> 
> 
> The layout of the clustering is not that important to me, my primary
> interest is the to get the right nodes into the right clusters.
> 
> 
> 
> Sincerely
> 
> 
> Henrik
> 
> 	[[alternative HTML version deleted]]
> 
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