![[Experimental]](figures/lifecycle-experimental.svg)
Usage
count_reachable(graph, mode = c("out", "in", "all", "total"))Arguments
- graph
The input graph.
- mode
Character constant, defines how edge directions are considered in directed graphs.
"out"counts vertices reachable via outgoing edges,"in"counts vertices from which the current vertex is reachable via incoming edges,"all"or"total"ignores edge directions. This parameter is ignored for undirected graphs.
Value
An integer vector of length vcount(graph).
The i-th element is the number of vertices reachable from vertex i
(including vertex i itself).
Details
Counts the number of vertices reachable from each vertex in the graph.
For each vertex in the graph, this function counts how many vertices are reachable from it, including the vertex itself. A vertex is reachable from another if there is a directed path between them. For undirected graphs, two vertices are reachable from each other if they are in the same connected component.
See also
components(), subcomponent(), is_connected()
Connected components
articulation_points(),
biconnected_components(),
component_distribution(),
decompose(),
is_biconnected()
Author
Gabor Csardi csardi.gabor@gmail.com
Examples
# In a directed path graph, the reachability depends on direction
g <- make_graph(~ 1 -+ 2 -+ 3 -+ 4 -+ 5)
count_reachable(g, mode = "out")
#> [1] 5 4 3 2 1
count_reachable(g, mode = "in")
#> [1] 1 2 3 4 5
# In an undirected graph, reachability is the same in all directions
g2 <- make_graph(~ 1 - 2 - 3 - 4 - 5)
count_reachable(g2, mode = "out")
#> [1] 5 5 5 5 5
# A graph with multiple components
g3 <- make_graph(~ 1 - 2 - 3, 4 - 5, 6)
count_reachable(g3, mode = "all")
#> [1] 3 3 3 2 2 1