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igraph (version 1.3.5)

is_dag: Directed acyclic graphs

Description

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

Usage

is_dag(graph)

Value

A logical vector of length one.

Arguments

graph

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

Author

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

Details

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

Examples

Run this code

g <- make_tree(10)
is_dag(g)
g2 <- g + edge(5,1)
is_dag(g2)

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