Create graphs from adjacency lists
An adjacency list is a list of numeric vectors, containing the neighbor vertices for each vertex. This function creates an igraph graph object from such a list.
graph.adjlist(adjlist, mode = c("out", "in", "all", "total"), duplicate = TRUE)
- The adjacency list. It should be consistent, i.e. the maximum throughout all vectors in the list must be less than the number of vectors (=the number of vertices in the graph). Note that the list is expected to be 0-indexed.
- Character scalar, it specifies whether the graph to create
is undirected (
allor total) or directed; and in the latter case, whether it contains the outgoing ( out) or the incoming ( in<
- Logical scalar. For undirected graphs it gives
whether edges are included in the list twice. E.g. if it is
TRUEthen for an undirected
Aincluded in the neigh
Adjacency lists are handy if you intend to do many (small) modifications to a graph. In this case adjacency lists are more efficient than igraph graphs.
The idea is that you convert your graph to an adjacency list by
get.adjlist, do your modifications to the graphs and
finally create again an igraph graph by calling
- An igraph graph object.
## Directed g <- graph.ring(10, dir=TRUE) al <- get.adjlist(g, mode="out") g2 <- graph.adjlist(al) graph.isomorphic(g, g2) ## Undirected g <- graph.ring(10) al <- get.adjlist(g) g2 <- graph.adjlist(al, mode="all") graph.isomorphic(g, g2) ecount(g2) g3 <- graph.adjlist(al, mode="all", duplicate=FALSE) ecount(g3) is.multiple(g3)