text - Word graph in R using Igraph

Question

I have a simple problem. I have 2 text documents and I want to make a graph of each document through Igraph or other similar library. I actually want to make a large graph combine both subgraphs of two documents. I tried the following code. But,

> Topic1 = c("I love Pakistan")
> Topic2 = c("Pakistan played well")
> src = data.frame(Topic1,Topic2)
> mycorpus = Corpus(VectorSource(src))
> tdm = as.matrix(TermDocumentMatrix(mycorpus))

Now, don't know what should do next. First graph of Topic1 will have 3 nodes and 3 edges, similarly, Second graph Topic2 will have 3 nodes and 3 edges. Now, I want o merge these two graph into one graph. The large graph now will have 5 nodes and 6 edges, where, node Pakistan will have 4 edges.

Anybody can help me?

question from:https://stackoverflow.com/questions/65862083/word-graph-in-r-using-igraph

Answer 1

Finally, I got the solution myself. First, we should make a graph of terms from Topic1. We will use every term that have frequency greater than 0.

tdm = as.matrix(TermDocumentMatrix(my))
x = names(tdm[,1][tdm[,1]>0])
k = t(combn(x,2))
g = graph_from_edgelist(k,directed = FALSE)
plot(g)

x2 = names(tdm[,2][tdm[,2]>0])
k2 = t(combn(x2,2))
g2 = graph_from_edgelist(k2,directed = FALSE)
plot(g2)

E1 = get.edgelist(g)
E2 = get.edgelist(g2)
E3 = rbind(E1,E2)
g3 = graph_from_edgelist(E3,directed = FALSE)
plot(g3)
g3 = simplify(g3,remove.multiple = TRUE, remove.loops = TRUE)