R: Drop, add or set the direction of an arc or an edge

arc operations {bnlearn}

R Documentation

Drop, add or set the direction of an arc or an edge

Description

Drop, add or set the direction of a directed or undirected arc (also known as edge).

Usage

# arc operations.
set.arc(x, from, to, check.cycles = TRUE, check.illegal = TRUE, debug = FALSE)
drop.arc(x, from, to, debug = FALSE)
reverse.arc(x, from, to, check.cycles = TRUE, check.illegal = TRUE, debug = FALSE)

# edge (i.e. undirected arc) operations
set.edge(x, from, to, check.cycles = TRUE, check.illegal = TRUE, debug = FALSE)
drop.edge(x, from, to, debug = FALSE)

Arguments

`x`	an object of class `bn`.
`from`	a character string, the label of a node.
`to`	a character string, the label of another node.
`check.cycles`	a boolean value. If `TRUE` the graph is tested for acyclicity; otherwise the graph is returned anyway.
`check.illegal`	a boolean value. If `TRUE` arcs that break the parametric assumptions of `x`, such as those from continuous to discrete nodes in conditional Gaussian networks, cause an error.
`debug`	a boolean value. If `TRUE` a lot of debugging output is printed; otherwise the function is completely silent.

Details

The set.arc() function operates in the following way:

if there is no arc between from and to, the arc from -> to is added.
if there is an undirected arc between from and to, its direction is set to from -> to.
if the arc to -> from is present, it is reversed.
if the arc from -> to is present, no action is taken.

The drop.arc() function operates in the following way:

if there is no arc between from and to, no action is taken.
if there is a directed or an undirected arc between from and to, it is dropped regardless of its direction.

The reverse.arc() function operates in the following way:

if there is no arc between from and to, it returns an error.
if there is an undirected arc between from and to, it returns an error.
if the arc to -> from is present, it is reversed.
if the arc from -> to is present, it is reversed.

The set.edge() function operates in the following way:

if there is no arc between from and to, the undirected arc from - to is added.
if there is an undirected arc between from and to, no action is taken.
if either the arc from -> to or the arc to -> from are present, they are replaced with the undirected arc from - to.

The drop.edge() function operates in the following way:

if there is no undirected arc between from and to, no action is taken.
if there is an undirected arc between from and to, it is removed.
if there is a directed arc between from and to, no action is taken.

Value

All functions return invisibly an updated copy of x.

Author(s)

Marco Scutari

Examples

data(learning.test)
res = gs(learning.test)

## use debug = TRUE to get more information.
set.arc(res, "A", "B")
drop.arc(res, "A", "B")
drop.edge(res, "A", "B")
reverse.arc(res, "A", "D")

[Package bnlearn version 4.3 Index]