Edge matrix of a graph
Transforms the adjacency matrix of a graph into an “edge matrix”.
edgematrix(E, inv=FALSE)
E |
a square matrix, representing the adjacency matrix of a graph. |
inv |
a logical value. |
In some matrix computations for graph objects the adjacency matrix of the graph is transformed into an “edge matrix”. Briefly, if E is the adjacency matrix of the graph, the edge matrix is A = sign(E+I)^T=[a_{ij}]. Thus, A has ones along the diagonal and if the graph has no edge between nodes i and j the entries a_{i,j} and a_{j,i} are both zero. If there is an arrow from j to i a_{i,j}=1 and a_{j,i} = 0. If there is an undirected edge, both a_{i,j}=a_{j,i}=1.
A |
the edge matrix of the graph.
If |
Giovanni M. Marchetti
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.
amat <- DAG(y ~ x+z, z~u+v) amat edgematrix(amat) edgematrix(amat, inv=TRUE)
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