edgematrix {ggm} | R Documentation |
Edge matrix of a graph
Description
Transforms the adjacency matrix of a graph into an “edge matrix”.
Usage
edgematrix(E, inv=FALSE)
Arguments
E |
a square matrix, representing the adjacency matrix of a graph. |
inv |
a logical value. |
Details
In some matrix computations for graph objects the adjacency matrix
of the graph is transformed into an “edge matrix”. Briefly,
if is the adjacency matrix of the
graph, the edge matrix is
.
Thus,
has ones along the diagonal
and if the graph has no edge between nodes
and
the entries
and
are both zero.
If there is an arrow from
to
and
. If there is an undirected edge, both
.
Value
A |
the edge matrix of the graph.
If |
Author(s)
Giovanni M. Marchetti
References
Wermuth, N. (2003). Analysing social science data with graphical Markov models. In: Highly Structured Stochastic Systems. P. Green, N. Hjort & T. Richardson (eds.), 47–52. Oxford: Oxford University Press.
See Also
Examples
amat <- DAG(y ~ x+z, z~u+v)
amat
edgematrix(amat)
edgematrix(amat, inv=TRUE)