igraph (version 0.5.3)

conversion: Convert a graph to an adjacency matrix or an edge list

Description

Sometimes it is useful to have a standard representation of a graph, like an adjacency matrix or an edge list.

Usage

get.adjacency(graph, type=c("both", "upper", "lower"),
       attr=NULL, names=TRUE, binary=FALSE, sparse=FALSE)
get.edgelist(graph, names=TRUE)

Arguments

graph
The graph to convert.
type
Gives how to create the adjacency matrix for undirected graphs. It is ignored for directed graphs. Possible values: upper: the upper right triangle of the matrix is used, lower: the lower left triangle of the matrix i
attr
Either NULL or a character string giving an edge attribute name. If NULL a traditional adjacency matrix is returned. If not NULL then the values of the given edge attribute are included in the adjacency m
names
Logical constant.

For graph.adjacenct it gives whether to assign row and column names to the matrix. These are only assigned if the name vertex attribute is present in the graph.

for get.edgelist it

binary
Logical, whether to return a binary matrix. This argument is ignored if attr is not NULL.
sparse
Logical scalar, whether to create a sparse matrix. The Matrix package must be installed for creating sparse matrices.

Value

  • A vcount(graph) by vcount(graph) (usually) numeric matrix for get.adjacency. (This can be huge!) Note that a non-numeric matrix might be returned if attr is a non-numeric edge attribute.

    A ecount(graph) by 2 numeric matrix for get.edgelist.

concept

  • Edge list
  • Adjacency list

Details

get.adjacency returns the adjacency matrix of a graph, a regular Rmatrix if sparse is FALSE, or a sparse matrix, as defined in the Matrix package, if sparse if TRUE. get.edgelist returns the list of edges in a graph.

See Also

graph.adjacency, read.graph

Examples

Run this code
g <- erdos.renyi.game(10, 2/10)
get.edgelist(g)
get.adjacency(g)
V(g)$name <- letters[1:vcount(g)]
get.adjacency(g)
E(g)$weight <- runif(ecount(g))
get.adjacency(g, attr="weight")

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