R: Graph queries

isAcyclic {ggm} | R Documentation

## Graph queries

### Description

Checks if a given graph is acyclic.

### Usage

    isAcyclic(amat, method = 2)

### Arguments

`amat` | a square Boolean matrix with dimnames, the adjacency matrix of a graph.
`method` | an integer 1 or 2 specifying the method used. If `method=1` the function calls the function `clusters` in package `igraph` to find the strong components: two nodes v and w are in the same strong component iff there are directed paths from v to w and from w to v. If `method=2` the function uses the `ggm` function `transClos`. Method 1 is faster.

### Value

a logical value, `TRUE` if the graph is acyclic and `FALSE` otherwise.

### Author(s)

David Edwards, Giovanni M. Marchetti

### References

Aho, A.V., Hopcroft, J.E. \& Ullman, J.D. (1983). Data structures and algorithms. Reading: Addison-Wesley.

### Examples

    ## A cyclic graph
    d <- matrix(0,3,3)
    rownames(d) <- colnames(d) <- c("x", "y", "z")
    d["x","y"] <- d["y", "z"] <- d["z", "x"] <- 1
    ## Test if the graph is acyclic
    isAcyclic(d)
    isAcyclic(d, method = 1)

[Package ggm version 2.3 Index]