Matrics to Graph coersions {graph} | R Documentation |
A collection of functions and methods to convert various forms of matrices into graph objects.
aM2bpG(aM) ftM2adjM(ft, W=NULL, V=NULL, edgemode="directed")
ft |
A matrix with two columns containing the from/to representation of graph edges. |
W |
An optional vector of edge weights. |
V |
An optional vector of node names. |
aM |
An affiliation matrix for a bipartite graph. |
edgemode |
Specifies if the resulting graph is to be directed or undirected |
In the fuction ftM2adjM
, a from/to
matrix is converted
into an adjacency
matrix (which can then be coerced directly into
a graphNEL-class
with as
. Ths first column of the
ft
represents the from
nodes and the second column
represents to
nodes. This representation does not allow for
unconnected nodes except with the V
argument (see below). The
edgemode
parameter can be used to specify if the desired output
is a directed or undirected graph.
Also in ftM2adjM
, W
is an optional vector of edge weights.
The order of the edge weights in the vector should correspond to the
order of the edges recorded in L
. If it is not specified, edge
weights of 1 are assigned by default. The V
argument is an
optional vector of node names. All nodes in ft
must be contained
in V
, but not all nodes in V
must be contained in
ft
. If V
is not specified, it is set to all nodes
represented in ft
or M
. Specifying V
is most useful
for creating a graph that includes nodes with degree 0.
aM
is an affiliation matrix as frequently used in social networks
analysis. The rows of aM
represent actors, and the columns
represent events. An entry of "1" in the ith row and jth column
represents affiliation of the ith actor with the jth event. Weighted
entries may also be used. aM2bpG
returns a graphNEL
object with
nodes consisting of the set of actors and events, and directed (possibly
weighted) edges from the actors to their corresponding events. If
plotted using Rgraphviz
and the dot
layout, the bipartite structure of
the graph returned by aM2bpG
should be evident.
An adjacency
matrix can be directly coerced into a
graphNEL
using the as
method. If the matrix is a
symmetric matrix, then the resulting graph will be undirected
,
otherwise it will be directed
.
For aM2bpG
, an object of class graphNEL
. For
ftM2adjM
, an adjacency matrix representation of the coerced graph.
Denise Scholtens
From <- c("A","A","C","C") To <- c("B","C","A","D") L <- cbind(From,To) W <- 1:4 M1 <- ftM2adjM(L,W, edgemode="undirected") M2 <- ftM2adjM(L) G1 <- as(M1, "graphNEL") G2 <- as(M2, "graphNEL")