igraph (version 0.5.5-2)

get.incidence: Incidence matrix of a bipartite graph

Description

This function can return a sparse of dense incidence matrix of a bipartite network. The incidence matrix is an n times m matrix, n and m are the number of vertices of the two kinds.x

Usage

get.incidence(graph, types=NULL, attr=NULL, names=TRUE, sparse=FALSE)

Arguments

graph

The input graph. The direction of the edges is ignored in directed graphs.

types

An optional vertex type vector to use instead of the type vertex attribute. You must supply this argument if the graph has no type vertex attribute.

attr

Either NULL or a character string giving an edge attribute name. If NULL a traditional incidence matrix is returned. If not NULL then the values of the given edge attribute are included in the incidence m

names

Logical scalar, if TRUE and the vertices in the graph are named (i.e. the graph has a vertex attribute called name), then vertex names will be added to the result as row and column names. Otherwise th

sparse

Logical scalar, if it is TRUE then a sparse matrix is created, you will need the Matrix package for this.

Value

• A sparse or dense matrix.

concept

• Bipartite graph
• Two-mode network
• Incidence matrix

Details

Bipartite graphs have a type vertex attribute in igraph, this is boolean and FALSE for the vertices of the first kind and TRUE for vertices of the second kind.

The vertex ids corresponding to rows and columns in the incidence matrix are returned as row/column names.

See Also

graph.incidence for the opposite operation.

Examples

g <- graph.bipartite( c(0,1,0,1,0,0), c(0,1,1,2,2,3) )
get.incidence(g)