Creating an adjacency list from a data.frame

Question

I have a data.frame with 2 columns: Node A, Node B. Each entry in the frame implies an edge in a graph between node A and B.

There must be a nice one-liner to convert this data.frame into an adjacency list. Any hints?

Answer 1

Since you tagged this igraph, how about using built in functionality?

> g <- graph.data.frame( edges )
> adjlist <- get.adjedgelist(g)

Only caveat is the vertices are zero indexed, which will be changing with igraph 0.6.