Compute an Edge Matrix or weight vector for a Graph
For our purposes an edge matrix is a matrix with two rows and as many columns as there are edges. The entries in the first row are the index of the node the edge is from, those in the second row indicate the node the edge is to.
If the graph is “undirected” then the duplicates option
can be used to indicate whether reciprocal edges are wanted. The
default is to leave them out. In this case the notions of from
and to are not relevant.
edgeMatrix(object, duplicates=FALSE)
eWV(g, eM, sep = ifelse(edgemode(g) == "directed", "->",
"--"), useNNames=FALSE)
pathWeights(g, p, eM=NULL)object |
An object that inherits from |
g |
An object that inherits from |
duplicates |
Whether or not duplicate edges should be produced for “undirected” graphs. |
eM |
An edge matrix |
sep |
a character string to concatenate node labels in the edge label |
useNNames |
a logical; if TRUE, node names are used in the edge label; if FALSE, node indices are used |
p |
a vector of node names constituting a path in graph |
Implementations for graphNEL, clusterGraph and
distGraph are available.
edgeMatrix returns a matrix with two rows, from and to, and as many columns
as there are edges. Entries indicate the index in the node vector that
corresponds to the appropriate end of the edge.
eWV uses the edge matrix to create an annotated vector of
edge weights.
pathWeights returns an annotated vector of edge weights
for a specified path in a graph.
A path through an undirected graph may have several representations as a named vector of edges. Thus in the example, when the weights for path b-a-i are requested, the result is the pair of weights for edges a–b and a–i, as these are the edge labels computed for graph g1.
R. Gentleman
set.seed(123)
g1 <- randomGraph(letters[1:10], 1:4, p=.3)
edgeMatrix(g1)
g2 <- new("clusterGraph", clusters=list(a=c(1,2,3), b=c(4,5,6)))
em2 <- edgeMatrix(g2)
eWV(g1, edgeMatrix(g1))
eWV(g1, edgeMatrix(g1), useNNames=TRUE)
pathWeights(g1, c("b", "a", "i"))Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.