zenplots (version 1.0.0)

graph_pairs: Turn pairs or paths into a graph

Description

Pairs are processed to produce a graph with the elements of the pairs as vertices and the pairs as undirected edges. The result can be displayed using plot().

Usage

graph_pairs(x, var.names = NULL, edgemode = c("undirected", "directed"))

Arguments

x

matrix or list of pairs along a zenpath. Can also be a list containing vectors representing paths in the graph. Every path must be of length at least 2 (i.e. each vector element of the list).

var.names

names of the variables appearing in x.

edgemode

type of edges to be used: either "undirected" (the default) or "directed" (in which case the order of the nodes in each pair matters).

Value

a graphNEL object; can be displayed using plot().

See Also

zenplot() which provides the zenplot.

Other tools related to constructing zenpaths: connect_pairs, extract_pairs, groupData, indexData, zenpath

Examples

# NOT RUN {
## Get some pairs
pairs <- matrix(c(1,2, 5,1, 3,4, 2,3, 4,2), ncol = 2, byrow = TRUE)
g <- graph_pairs(pairs)
## which can be displayed using plot(g) 
## if the graph package is installed.
library(graph) 
plot(g) 

## Build a graph from a list of paths
paths <- list(3:1, c(3,5,7), c(1,4,7), c(6,7))
gp <- graph_pairs(paths)
## graph package draws with grid, so clear
grid.newpage()
plot(gp)

## Nodes do not need to be numbers
alpha_paths <- list(letters[3:1], letters[c(3,5,7)], 
                    letters[c(1,4,7)], letters[c(6,7)])
grid.newpage()
plot(graph_pairs(alpha_paths))

## Zenplots never uses this feature but you could
## build a directed graph with a single isolated node
dg <- graph_pairs(alpha_paths, 
                  var.names = c(letters[1:7], "ALONE"),
                  edgemode = "directed" )
grid.newpage()
plot(dg)

# }