I'm using the igraph library to create two graphs in the 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
This two graphs, g.v1 and g.merchant , are disjoint. I would like to connect the g.merchant graph, which only has 1 vertex, with any of the 6 vertices of the g.v1 graph. The new graph will have 7 vertices. How do I do this?
The code below will solve your problem. In addition, it randomly selects one of the vertices of g.v1 to make the connection with the g.merchant graph.
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<-1plot(g.merchant) 
g.novo<-g.v1+g.merchantv.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 g.merchant , its unique vertex was identified as 1. When you join the two graphs, the number of this vertex has been updated to 7.