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rgraphnodesedgessubgraph

R: Plot the famous "6 degrees of separation" (Kevin Bacon)

I am trying to write some R code that shows degrees of separation between friends. That is, suppose I pick the "node" with the arrow pointing towards it, and I say "degree = 3", I would like to be able to identify the following path in this network:enter image description here

I think I found a previous post on stackoverflow that answers a similar question: R Igraph subgraph given node index and number of nodes to include in the graph

Suppose I create some fake network data :

library(igraph)
file <-data.frame(
    
    "source" = c(
        "John",
        "John",
        "Tim",
        "Tim",
        "Alex",
        "Andrew",
        "Andrew",
        "Andrew",
        "Oliver",
        "Oliver",
        "Oliver",
        "Matt",
        "Steven",
        "Steven",
        "Steven",
        "Matt",
        "Charles",
        "Charles",
        "Charles",
        "Sean",
        "Ted",
        "Ryan",
        "Ryan",
        "Ryan",
        "Ted",
        "Phil",
        "Phil",
        "Phil",
        "Sam",
        "Toby",
        "Toby",
        "Donald",
        "Donald",
        "Donald",
        "Mitch",
        "Mitch",
        "Mitch"),
    
    "target" = c("Sam",
                 "Tim",
                 "Alex",
                 "Matt",
                 "Andrew",
                 "Sean",
                 "Peter",
                 "Ben",
                 "Kevin",
                 "Thomas",
                 "Dave",
                 "Steven",
                 "Kenny",
                 "Derek",
                 "CJ",
                 "Charles",
                 "Ivan",
                 "Kyle",
                 "Andrew",
                 "Ted",
                 "Ryan",
                 "Daniel",
                 "Chris",
                 "Scott",
                 "Phil",
                 "Henry",
                 "George",
                 "Paul",
                 "Toby",
                 "Donald",
                 "Mitch",
                 "Jack",
                 "Luke",
                 "Myles",
                 "Elliot",
                 "Harvey",
                 "Owen")
    
)

graph <- graph.data.frame(file, directed=F)
graph <- simplify(graph)
plot(graph)

Is this the correct code for plotting 3 degrees of separation for "John"?

distan <- 3

subnetwork <- induced.subgraph(graph, vids = as.vector(unlist(neighborhood(graph, distan, nodes = "John", mode = 'all'))))

plot(subnetwork)

Is there a way to find out "who has the most friends" in this network? (the node with the most connections)

Thanks

Solution

  • Your code works but I believe that use of neighborhood is deprecated. Instead, it might be better to use.

    distan <- 3
subnetwork <- induced.subgraph(graph, unlist(ego(graph, order=3, nodes="John")))

    To find out who has the most friends, use the degree function.

    degree(graph)
   John     Tim    Alex  Andrew  Oliver    Matt  Steven Charles    Sean     Ted 
      2       3       2       5       3       3       4       4       2       3 
   Ryan    Phil     Sam    Toby  Donald   Mitch   Peter     Ben   Kevin  Thomas 
      4       4       2       3       4       4       1       1       1       1 
   Dave   Kenny   Derek      CJ    Ivan    Kyle  Daniel   Chris   Scott   Henry 
      1       1       1       1       1       1       1       1       1       1 
 George    Paul    Jack    Luke   Myles  Elliot  Harvey    Owen 
      1       1       1       1       1       1       1       1

    Andrew has the most friends.