[R] Weighted Graph Link strength ( I am making mistake please help)

Sur Nathan surendar.swaminathan at gmail.com
Wed Mar 25 19:56:40 CET 2009


Hello R experts,

   I went through R mailing,Nabble R.I could not find solution.Can someone
help me.

I have undirected Graph.

Here  is an example of spreadsheet I have( Unique 3559 Nodes)

snippet of 4 rows.

Node1	Node2	Weights
1	2	5
2	3	30
2	4	30
1	4	5
3	4	30
1	3	2


I created a program reading the csv and created a Adjacency matrix.From the
adjacency matrix I created graph.I am not sure the mistake I am making.

Program to read and create Matrix

matrixmy<-scan("test.csv",sep=",",skip=1)

arr=array(0,dim=c(4,4))
a<-1

while(a<=length(matrixmy))
 {
 i=matrixmy[a]
 a<-a+1
 j=matrixmy[a]
 a<-a+1

 k=matrixmy[a]

 
arr[i,j]<-k
arr[j,i]<-k

 a<-a+1
 }

Created matrix

mat1<-matrix(data=arr,nrow=4,ncol=4)

g<-graph.adjacency(adjmatrix=mat1,mode=c("undirected"))

betweenness(g)

The answer I get is 

0 0 0 0 

I was expecting Node 1 will have high value.

Can someone tell me why it is happening like this.

Thanks in advance.

Nathna


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