Directed acyclic graphs

This function tests whether the given graph is a DAG, a directed acyclic graph.

is_dag(graph)

Arguments

graph

The input graph. It may be undirected, in which case FALSE is reported.

Value

A logical vector of length one.

Details

is_dag() checks whether there is a directed cycle in the graph. If not, the graph is a DAG.

See also

Graph cycles feedback_arc_set(), feedback_vertex_set(), find_cycle(), girth(), has_eulerian_path(), is_acyclic(), simple_cycles()

Other structural.properties: bfs(), component_distribution(), connect(), constraint(), coreness(), degree(), dfs(), distance_table(), edge_density(), feedback_arc_set(), feedback_vertex_set(), girth(), is_acyclic(), is_matching(), k_shortest_paths(), knn(), reciprocity(), subcomponent(), subgraph(), topo_sort(), transitivity(), unfold_tree(), which_multiple(), which_mutual()

Author

Tamas Nepusz ntamas@gmail.com for the C code, Gabor Csardi csardi.gabor@gmail.com for the R interface.

Related documentation in the C library

is_dag().

Examples

g <- make_tree(10)
is_dag(g)
#> [1] TRUE
g2 <- g + edge(5, 1)
is_dag(g2)
#> [1] FALSE