Drawing graph G=(V,E) in R

Question

I would like to draw standard G=(V,E) graph in R either by ggplot or some R built-in functions.

I have a data frame containing vertices coords:

> V

      x        y

1  589.3438 6422.883

2 8762.6921 7789.147

3 7973.0883 4552.745

4 4100.8408 8108.702

5 6049.3329 6547.239

and a zero-one symetric matrix representing edges:

> E

       [,1] [,2] [,3] [,4] [,5]

 [1,]    0    0    0    1    0

 [2,]    0    0    1    0    1

 [3,]    0    1    0    0    1

 [4,]    1    0    0    0    1

 [5,]    0    1    1    1    0

I plot vertices using:

plotGraph <- function() {

  qplot(x,

        y,

        data=V,

        xlim=c(0,SIZE),

        ylim=c(0,SIZE),

        main="Graph"

  )

}

How could I draw graph edges on the same plot? Or how do I plot a single edge from (x1, y1) to (x2, y2)?

Any help would be appreciated.

Answer 1

If using igraph is an option, I would recommend it. It's a very useful package when working with graphs. Here's how I would do it using igraph:

library(igraph)

# convert V and E to matrices
V <- data.matrix(V)
g <- graph_from_adjacency_matrix(E, mode="undirected")

plot.igraph(g, layout = V)

Alternatively, if you want a ggplot-flavored method, you can use ggnet2 from the GGally package:

library(GGally)

V <- data.matrix(V)
# with ggnet2 you don't have to convert E to a graph

ggnet2(net = E, mode = V )

Drawing graph G=(V,E) in R

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