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I would like some help getting started in creating a network in igraph in R.

My data looks like this:

data <- data.frame(Country = c("Argentina", "Bolivia", "Chile", "France", "Guam", "US"), Counts = c(2,8,1,5,3,35))

Where the counts column is the count of how many times these countries appeared in a specific search.

Every tutorial I am reading on igraph has a way to graph nodes and edges. With edges usually containing a from and to column. But in this dataset, the countries are not linked. I just need help getting this code started. I have included a picture on what my end result should look like - with the thickness of the lines being proportional to the counts column. Is this possible? enter image description here

Szabolcs
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Purrsia
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    I think you still need to add a middle node that connects to all other nodes `Country` in your sample, then change its size to zero. check the answer on [this](https://stackoverflow.com/questions/14399594/can-we-vary-the-text-size-along-with-node-size-in-r-igraph) for node size – Vida Dec 14 '22 at 04:13

1 Answers1

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As pointed out by @Vida, we need to construct a center.

library(igraph)
nations   <- data.frame(Country = c("Argentina", "Bolivia", "Chile", "France", "Guam", "US"),
                         Counts = c(2,8,1,5,3,35),
                     Population = c(45.195, 11.673, 19.116, 65.625, 0.172, 332.403)
             )
center <- setNames(data.frame("c",2,0), names(nations))
vtx    <- rbind(center, nations)
rel    <- data.frame( from = head(vtx$Country, 1),
                        to = tail(vtx$Country),
                     width = tail(vtx$Counts)   
             )                    


## >?graph_from_data_frame, read the docs.
g <- graph_from_data_frame(rel,  directed = FALSE, vtx )
vertex_attr_names(g)
g

Plotting a nice graph is an art in itself. See for example a recent query: How can I make edge betweenness with igraph in R?

## >?plot.igraph, read the docs.
cols             <- c("white", "green", "black", "brown", "blue", "yellow", "purple")
V(g)$color       <- "white"
V(g)$size        <- c(2, rep(40, nrow(vtx)-1))
V(g)$frame.color <- cols
V(g)$frame.width <- 4
E(g)$color       <- tail(cols)
plot(g, layout=layout_as_star)

## An alternative is to change the vertex size.
size <- (rank(V(g)$Population) - 1) * 5 
dev.new(); plot(g, layout=layout_as_star, vertex.size = size , edge.width=4)
clp
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  • Thank-you very much! This worked perfectly and it was just the start I needed to get this graph going. -Grateful to you! – Purrsia Dec 15 '22 at 00:04