| unfold_tree {igraph} | R Documentation |
Convert a general graph into a forest
Description
Perform a breadth-first search on a graph and convert it into a tree or forest by replicating vertices that were found more than once.
Usage
unfold_tree(graph, mode = c("all", "out", "in", "total"), roots)
Arguments
graph |
The input graph, it can be either directed or undirected. |
mode |
Character string, defined the types of the paths used for the breadth-first search. “out” follows the outgoing, “in” the incoming edges, “all” and “total” both of them. This argument is ignored for undirected graphs. |
roots |
A vector giving the vertices from which the breadth-first search is performed. Typically it contains one vertex per component. |
Details
A forest is a graph, whose components are trees.
The roots vector can be calculated by simply doing a topological sort
in all components of the graph, see the examples below.
Value
A list with two components:
tree |
The result, an |
vertex_index |
A numeric vector, it gives a mapping from the vertices of the new graph to the vertices of the old graph. |
Author(s)
Gabor Csardi csardi.gabor@gmail.com
See Also
Other structural.properties:
bfs(),
component_distribution(),
connect(),
constraint(),
coreness(),
degree(),
dfs(),
distance_table(),
edge_density(),
feedback_arc_set(),
girth(),
is_acyclic(),
is_dag(),
is_matching(),
k_shortest_paths(),
knn(),
reciprocity(),
subcomponent(),
subgraph(),
topo_sort(),
transitivity(),
which_multiple(),
which_mutual()
Examples
g <- make_tree(10) %du% make_tree(10)
V(g)$id <- seq_len(vcount(g)) - 1
roots <- sapply(decompose(g), function(x) {
V(x)$id[topo_sort(x)[1] + 1]
})
tree <- unfold_tree(g, roots = roots)