SimpleGraphOperations function

Simple graph operations

Finds the boundary, children, parents of a subset of nodes of a graph.

bd(nn, amat)
ch(nn, amat)
pa(nn, amat)

Arguments

• nn: a vector of nodes. It may either a numeric vector, or a character vector. If it is character vector must be a subset of the rownames of the edge matrix.
• amat: a square matrix with dimnames specifying the adjacency matrix of the graph

Details

For definitions of the operators see Lauritzen (1996).

Returns

The operators return a character vector specifying the boundary or the children or the parents of nodes nn

in the graph. This is a numeric or a character vector depending on the mode of nn.

References

Lauritzen, S. (1996). Graphical models. Oxford: Clarendon Press.

Author(s)

Giovanni M. Marchetti

See Also

UG, DAG

Examples

## find boundary of a subset of nodes of a DAG
G <- DAG(y ~ x+b+a, b~a, x~a)
bd("b", G)
bd(c("b", "x"), G)
bd("x", G)
bd(c("x","b"), G)
## find boundary of a subset of nodes of an UG
G <- UG(~ y*x*z + z*h*v)
bd("z", G)
bd(c("y", "x"), G)
bd("v", G)
bd(c("x","v"), G)
## children of a subset of nodes of a DAG
G <- DAG(y ~ x+b+a, b~a, x~a)
ch("b", G)
ch(c("b", "x"), G)
ch("x", G)
ch(c("a","x"), G)
## parents of a subset of nodes of a DAG
pa("b", G)
pa(c("b", "x"), G)
pa("x", G)
pa(c("x","b"), G)