"Join" two graphs in R

Question

I’m using the library igraph to create two graphs in R:

g.v1 <- graph.full(6, directed= TRUE)
E(g.v1)$weight <- 1

g.merchant <- graph.empty(1, directed=TRUE)
E(g.merchant)$weight <- 1

These two graphs, g.v1 and g.merchant, are disjoint. I would like to connect the graph g.merchant, which has only 1 vertex, with Qalquer one of the 6 vertices of the graph g.v1. The new graph will have 7 vertices. How do I do this ?

Answer 1

The code below solves your problem. Even, it randomly selects one of the vertices of the g.v1 to connect to the graph g.merchant.

library(igraph)

g.v1 <- graph.full(6, directed= TRUE)
E(g.v1)$weight <- 1
plot(g.v1)

g.merchant <- graph.empty(1, directed=TRUE)
E(g.merchant)$weight <- 1
plot(g.merchant)

g.novo <- g.v1 + g.merchant
v.aleatorio <- sample(unique(V(g.v1)), 1)
g.novo <- g.novo + path(v.aleatorio, 7, v.aleatorio)
plot(g.novo)

Note that in the first Plot of the g.merchant, its single vertex has been identified as 1. By joining the two graphs, the number of this vertex has been updated to 7.