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Networking: creating a graph object from an event - Node Data using igraph

I want to make a network object for an igraph from event note data.

For example, I have data similar to this.

 Event  Person
  1     Obama
  1     Putin
  1     Abe
  1     Cameron 
  2     Putin
  2     Xi
  2     Merkel
  3     Obama
  3     Abe
  3     Xi
  3     Merkel

I am assuming everyone has connections in the same case. Obama, Putin, Abe and Cameron have connections because they are all in the first case. Based on this data, Obama and Abe have two connections because they are both in case 1 and 3.

With this data, I want to calculate the degree / internecine / closeness. In order to calculate these centralities, I need to have a graph object. How can I create a graph object or adjacency matrix to calculate the three centrality scores?

I am sorry for this basic question, but I am new to using R for network analysis.

Thank you in advance!

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2 answers


Assuming you are reading your data into a data.frame with a name dd

, you can get a neighboring matrix with

X <- with(dd, table(Event, Person))
adj <- crossprod(X,X)

#          Person
# Person    Abe Cameron Merkel Obama Putin Xi
#   Abe       2       1      1     2     1  1
#   Cameron   1       1      0     1     1  0
#   Merkel    1       0      2     1     1  2
#   Obama     2       1      1     2     1  1
#   Putin     1       1      1     1     2  1
#   Xi        1       0      2     1     1  2

You have several options for how you want to turn this into a graph object, but most likely use graph.adjacency

. Here's one way



gg<-graph.adjacency(adj, mode="upper", weighted=TRUE, diag=FALSE);
plot(gg,  edge.width=E(gg)$weight)

enter image description here

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This is a bipartite graph and you want a projection of it.



txt <- "Event  Person
          1     Obama
          1     Putin
          1     Abe
          1     Cameron 
          2     Putin
          2     Xi
          2     Merkel
          3     Obama
          3     Abe
          3     Xi
          3     Merkel
"

data <- read.table(textConnection(txt), header = TRUE)
BG <- graph.data.frame(data, directed = FALSE)
V(BG)$type <- grepl("^[0-9]+$", V(BG)$name)

bipartite.projection(BG)[[1]]
#> IGRAPH UNW- 6 13 -- 
#> + attr: name (v/c), weight (e/n)
#> + edges (vertex names):
#>  [1] Obama--Putin   Obama--Abe     Obama--Cameron Obama--Xi      Obama--Merkel 
#>  [6] Putin--Abe     Putin--Cameron Putin--Xi      Putin--Merkel  Abe  --Cameron
#> [11] Abe  --Xi      Abe  --Merkel  Xi   --Merkel
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