Re: [igraph] Betweenness in weighted adjacency matrix

[Tamás Nepusz]

Hi,

> Import the txt file which looks as following (The first row specifies the 
> code for the different nodes, the other rows specifies the weights of edges).
How come that your input file is not a square matrix? It seems to have 8 rows 
and 13 columns -- where are the 5 missing rows and the 5 missing node names?

Otherwise what you do seems okay for me.

> IS it ok for igraph to have the name of the nodes just in the first row and 
> not in the first column to generate an adjacency matrix? i have read 
> somewhere it is the same as having the first column with 'A','B','C',etc
igraph doesn't care -- it does not read your file, it reads the matrix that you 
loaded with read.table. If the matrix looks fine in R, then it should be okay 
for igraph as well.

> I want then to calculate the betweenness, that will return a result for each 
> node, but I am not sure whether the weights are inserted correctly in the 
> function.
Seems okay for me, assuming that your input matrix is correct -- which is still 
a bit weird for me because of the missing rows.

> Is there a way I can check the results using other programs?
Of course -- find another program that can calculate weighted betweenness 
scores and compare the results ;) One possible option is the NetworkX module 
for Python if you know the Python language. (igraph also has a Python interface 
but it would be quite useless to compare igraph in Python vs igraph in R 
because they use the same implementation).

-- 
T.