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redges

Is there an R function to get the unique edges in an undirected (not directed) network?

I want to count the number of the unique edges in an undirected network, e.g, net

   x  y
1  A  B
2  B  A
3  A  B

There should be only one unique edge for this matrix, because edges A-B and B-A are same for the undirected network.

For the directed network I can get the number of unique edges by:

nrow(unique(net[,c("x","y"]))

But this doesn't work for the undirected network.

Solution

  • Given that you are working with networks, an igraph solution:

    library(igraph)

as_data_frame(simplify(graph_from_data_frame(dat, directed=FALSE)))

    Then use nrow

    Explanantion

    dat %>% 
  graph_from_data_frame(., directed=FALSE) %>% # convert to undirected graph
  simplify %>%                                 # remove loops / multiple edges
  as_data_frame                                # return remaining edges