get.inducedSubgraph {network}R Documentation

Retrieve Induced Subgraphs and Cuts

Description

Given a set of vertex IDs, get.inducedSubgraph returns the subgraph induced by the specified vertices (i.e., the vertices and all associated edges). Optionally, passing a second set of alters returns the cut from the first to the second set (i.e., all edges passing between the sets), along with the associated endpoints. In both cases, the result is returned as a network object, with all attributes of the selected edges and/or vertices (and any network attributes) preserved.

Usage

get.inducedSubgraph(x, v, alters = NULL)
x %s% v

Arguments

x

an object of class network.

v

a vector of vertex IDs, or, for %s%, optionally a list containing two disjoint vectors of vertex IDs (see below).

alters

optionally, a second vector of vertex IDs. Must be disjoint with v.

Details

For get.inducedSubgraph, v must be a vector of vertex IDs. If alter=NULL, the subgraph induced by these vertices is returned. Calling %s% with a single vector of vertices has an identical effect.

Where alters is specified, it must be a vector of IDs disjoint with v. Where both are given, the edges spanning v and alters are returned, along with the vertices in question. (Technically, only the edges really constitute the “cut,” but the vertices are included as well.) The same result can be obtained with the %s% operator by passing a two-element list on the right hand side; the first element is then interpreted as v, and the second as alters.

Any network, vertex, or edge attributes for the selected network elements are retained (although features such as vertex IDs and the network size will typically change). These are copies of the elements in the original network, which is not altered by this function.

Value

A network object containing the induced subgraph.

Author(s)

Carter T. Butts buttsc@uci.edu

See Also

network, network.extraction

Examples

#Load the Drabek et al. EMON data
data(emon)

#For the Mt. St. Helens, EMON, several types of organizations are present:
type<-emon$MtStHelens %v% "Sponsorship"

#Plot interactions among the state organizations
plot(emon$MtStHelens %s% which(type=="State"), displaylabels=TRUE)

#Plot state/federal interactions
plot(emon$MtStHelens %s% list(which(type=="State"), 
    which(type=="Federal")),  displaylabels=TRUE)

#Plot state interactions with everyone else
plot(emon$MtStHelens %s% list(which(type=="State"), 
    which(type!="State")), displaylabels=TRUE)

[Package network version 1.7 Index]