pcalg (version 1.0-0)

plotSG: Plot the neighbourhood of a specific node in a graph object

Description

This function plots a subgraph for a specified starting node and a given graph. The subgraph consists of those nodes, that can be reached from the starting node by passing no more than a specified number of edges.

Usage

plotSG( graphObj, y, dist, amat = NA, directed = TRUE )

Arguments

graphObj

Graph object.

y

Starting node.

dist

Distance of nodes included in subgraph from starting node y.

amat

Adjacency matrix of skeleton graph (optional).

directed

Boolean; should the plotted subgraph be directed?

Value

• A graph object containing the subgraph

Details

Commencing at the starting point 'y' the function looks for the neighbouring nodes. Beginning with direct parents and children it will continue hierarchically through the distances to 'y'. If 'directed' is set to TRUE the orientation of the edges is taken from the initial graph.

Examples

## generate a random DAG:
p <- 10
set.seed(45)
myDAG <- randomDAG(p, prob = 0.3)

## plot whole the DAG
plot(myDAG, main = "randomDAG(10, prob = 0.2)")

x11()
par(mfrow = c(3,2))
## plot the neighbours of node number 8 up to distance 1
plotSG(myDAG, 8, 1, directed = TRUE)
plotSG(myDAG, 8, 1, directed = FALSE)

## plot the neighbours of node number 8 up to distance 2
plotSG(myDAG, 8, 2, directed = TRUE)
plotSG(myDAG, 8, 2, directed = FALSE)

## plot the neighbours of node number 8 up to distance 3
plotSG(myDAG, 8, 3, directed = TRUE)
plotSG(myDAG, 8, 3, directed = FALSE)

## Note that the layout of the subgraph might be different than in the
## orignial graph, but the graph structure is identical