arc4gn: adds or remove some arc(s) to or from a gn object
In g4n: graph for networks

Description Usage Arguments Value Examples

Adds [removes] zero, one arc or a series of arcs to [from] a gn and returns the gn so modified. When arcs to add already exist, nothing is done. When arc to remove does not exist, nothing is done.

1	arc4gn(gn, from, to, add=TRUE)

`gn`	The gn object
`from`	vector of ion describing the starting nodes of the arcs to add or remove.
`to`	vector of ion describing the ending nodes of the arcs to add or remove.
`add`	(=TRUE) Adding? (or removing).

The modified gn object.

 g4n3k("RESET"); # needed only for R checking, to be forgotten
 gn1 <- g4n.gn7;
 gn2 <- arc4gn(gn1, c("A", "C"), c("E", "E"));
 gg1 <- arc4gn(gn2, "A", "B", FALSE);