R help - May 2008 - For Social Network Analysis-Graph Analysis - How to convert 2 mode data to 1 mode data?

Hi,

 

Does anyone know of a package in R that has a function to convert
network data (e.g. an adjacency matrix or ) from 2-mode to 1-mode?  I am
conducting social network analysis.  I know that Pajek has this function
under Net --> Transform --> 2-mode to 1-mode --> Rows.  I have searched
the documentation under packages 'sna', 'network',
'igraph', and
'dynamicgraph' but I was not able to identify a comparable function.  

 

I would just export my data to Pajek and import it to R, but I'm going
to have to generate hundreds of these graphs, so it would take quite a
bit of time to do it this way.  

 

Thanks,

 

Solomon

 


	[[alternative HTML version deleted]]

Solomon, if i understand two-mode networks properly (they're bipartite,
right?),
then this is not hard to do with igraph. Basically, for each vertex create an 
order=2 neighborhood, and then create a graph from the adjacency list,
it is something like this:

two.to.one <- function(g, keep) {
  neis <- neighborhood(g, order=2)
  neis <- lapply(seq(neis), function(x) neis[[x]][ neis[[x]] != x-1]) ## drop
self-loops
  neis <- lapply(neis, function(x) x[ x %in% keep ])                  ## keep
only these
  neis <- lapply(seq(neis), function(x) t(cbind(x-1, neis[[x]])))     ##
create edge lists
  neis[-keep-1] <- NULL                                               ##
these are not needed
  neis <- matrix(unlist(neis), byrow=TRUE, nc=2)                      ## a
single edge list
  neis <- neis[ neis[,1] > neis[,2], ]                                ##
count an edge once only
  mode(neis) <- "character"
  g2 <- graph.edgelist(neis, dir=FALSE)
  V(g2)$id <- V(g2)$name                                              ##
'id' is used in Pajek
  g2
}

It does not check that the graph is indeed two-mode, and it keeps the 
vertices given in the 'keep' argument. 'keep' is made of igraph
vertex ids.
You can use it like this:

g <- graph.ring(10)
keep <- seq(0,8,by=2) ## we keep the 'even' vertices

g2 <- two.to.one(g, keep)
write.graph(two.to.one(g, keep), format="pajek",
file="/tmp/a.net")

I haven't tested it much. We'll have a better function in the next
igraph version.
Gabor

On Fri, May 09, 2008 at 03:37:05PM -0400, Messing, Solomon O.
wrote:
> Hi,
> 
>  
> 
> Does anyone know of a package in R that has a function to convert
> network data (e.g. an adjacency matrix or ) from 2-mode to 1-mode?  I am
> conducting social network analysis.  I know that Pajek has this function
> under Net --> Transform --> 2-mode to 1-mode --> Rows.  I have
searched
> the documentation under packages 'sna', 'network',
'igraph', and
> 'dynamicgraph' but I was not able to identify a comparable
function.
> 
>  
> 
> I would just export my data to Pajek and import it to R, but I'm going
> to have to generate hundreds of these graphs, so it would take quite a
> bit of time to do it this way.  
> 
>  
> 
> Thanks,
> 
>  
> 
> Solomon
> 
>  
> 
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
-- 
Csardi Gabor <csardi at rmki.kfki.hu>    UNIL DGM

Please stay on the list.

On Tue, May 13, 2008 at 06:05:15PM -0400, Messing, Solomon O.
wrote:
> Gabor,
> 
> By the way, this seems to work:
I'm a bit lost. So now you're converting your data frame 
to a matrix? Why? Or you're doing the two-mode to one-mode
conversion here? It does not seem so to me.

Btw. there is a get.adjacency function in igraph to convert 
a graph to an adjacency matrix.

G.
> 
> df.to.nxn <- function( x, y ){
> # x values will be the N x N values   
>     M <- matrix( nrow = length( unique( x ) ), ncol = length( unique( x
> ) ), 
>           dimnames = list( unique( x ), unique( x ) ) )
>     M[ 1:length( unique( x ) ), 1:length( unique( x ) ) ] <- 0
> # initialize the values to 0 
>     for( i in 1:length( x ) ) {
> # iterate through rows of data    
>             index = which( y == y[i] )                    
>                 M[ as.character( x[ index ] ), as.character( x[ index ]
> ) ] = 1        
>      }
> M
> # return M, an N x N matrix
> }
-- 
Csardi Gabor <csardi at rmki.kfki.hu>    UNIL DGM

All, 

There is a simple solution to this problem using R's matrix algebra
commands.  I describe in detail at 
http://www.stanford.edu/~messing/Affiliation%20Data.html
http://www.stanford.edu/~messing/Affiliation%20Data.html .  

Best wishes,

-Solomon
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