Returns an adjacency list from an edge list
get_adj_list(el, n_nodes)
An adjacency list for the network
An edge list as a data.frame with columns head
and tail
The size number of node in the network
The adjacency list is a list
of length n_nodes
. The entry for each node
is a integer vector containing the index of all the nodes connected to it.
This layout makes it directly subsetable in O(1) at the expanse of memory
usage.
To get all connections to the nodes 10 and 15 : unlist(adj_list[c(10, 15)]