gRbase (version 1.6-12)

is.DAG: Check properties of graphs.

Description

Check if a graph is 1) a directed acyclic graph (DAG), 2) an undirected graph (UG), 3) a triangulated (chordal) undirected graph (TUG). A graph represented as 1) graphNEL (from the graph package), 2) an adjacency matrix, 3) a sparse adjacency matrix (a dgCMatrix from the Matrix package).

Usage

is.DAG(object)
is.UG(object)
is.TUG(object)
is.adjMAT(x)

Arguments

object

A graph represented as 1) graphNEL (from the graph package), 2) an adjacency matrix, 3) a sparse adjacency matrix (a dgCMatrix from the Matrix package).

x

Any object. If the object is a quadratic matrix with 0's on the diagonal then it is an adjacency matrix.

See Also

dag, ug

Examples

## DAGs
dagNEL  <- dag(~a:b:c+c:d:e, result="NEL")
dagMAT  <- dag(~a:b:c+c:d:e, result="matrix")
dagMATS <- dag(~a:b:c+c:d:e, result="Matrix")

## Undirected graphs
ugNEL  <- ug(~a:b:c+c:d:e, result="NEL")
ugMAT  <- ug(~a:b:c+c:d:e, result="matrix")
ugMATS <- ug(~a:b:c+c:d:e, result="Matrix")

## Is it a DAG?
is.DAG(dagNEL)
is.DAG(dagMAT)
is.DAG(dagMATS)

is.DAG(ugNEL)
is.DAG(ugMAT)
is.DAG(ugMATS)

## Is it an undirected graph
is.UG(dagNEL)
is.UG(dagMAT)
is.UG(dagMATS)

is.UG(ugNEL)
is.UG(ugMAT)
is.UG(ugMATS)

## Is it a triangulated (i.e. chordal)  undirected graph
is.TUG(dagNEL)
is.TUG(dagMAT)
is.TUG(dagMATS)

is.TUG(ugNEL)
is.TUG(ugMAT)
is.TUG(ugMATS)

## Example where the graph is not triangulated
ug2NEL  <- ug(~a:b+b:c+c:d+d:a, result="NEL")
ug2MAT  <- ug(~a:b+b:c+c:d+d:a, result="matrix")
ug2MATS <- ug(~a:b+b:c+c:d+d:a, result="Matrix")

is.TUG(ug2NEL)
is.TUG(ug2MAT)
is.TUG(ug2MATS)

## Bidirected graphs
edgemode(ugNEL)
edgemode(ugNEL) <- "directed"
edgemode(ugNEL)
is.DAG(ugNEL)
is.UG(ugNEL)