Transformation of a DAG into an essential graph {MXM}

Transforms a DAG into an essential graph

Description

Transforms a DAG into an essential graph.

Usage

dag2eg(dag, type = NULL) 

Arguments

dag

The graph matrix as produced from pc.or or any other algorithm which produces directed graphs. A DAG in general.

type

This can be either NULL or 1 or 2. type = 1 means that the matrix contains 0, 1, 2, 3 where G[i, j] = g[j, i] = 0, means there is no edge between nodes i and j, G[i, j] = g[j, i] = 1, there is an edge between nodes i and j and G[i, j] = 2 and G[j, i] = 3 means that there is an arrow from node i to node j. If type 2, the matrix contains 0 for no edge and 1 for a directed edge. In this case, G[i,j]=1 and G[j,i]=0 means that there is an arrow from node i to node j. If you are not sure of what you have, just leave it NULL, the function will check to which case your matrix belongs.

Details

The function is an R translation from an old matlab code.

Value

The matrix of the essential graph.

Author(s)

Ioannis Tsamardinos and Michail Tsagris

R implementation and documentation: Ioannis Tsamardinos <[e-mail]> and and Michail Tsagris [e-mail]

References

Chickering, D.M. (1995). A transformational characterization of equivalent Bayesian network structures. Proceedings of the 11th Conference on Uncertainty in Artificial Intelligence, Montreal, Canada, 87-98.

See Also

plotnetwork, is.dag, topological_sort

Examples

# simulate a dataset with continuous data
y <- rdag(1000, 10, 0.3)
tru <- y$G 
eg <- dag2eg(tru)
par( mfrow = c(1, 2) )
plotnetwork(tru)
plotnetwork(eg)