gplot.target: Display a Graph in Target Diagram Form

In sna: Tools for Social Network Analysis

Display a Graph in Target Diagram Form

Description

Displays an input graph (and associated vector) as a "target diagram," with vertices restricted to lie at fixed radii from the origin. Such displays are useful ways of representing vertex characteristics and/or local structural properties for graphs of small to medium size.

Usage

gplot.target(dat, x, circ.rad = (1:10)/10, circ.col = "blue", 
    circ.lwd = 1, circ.lty = 3, circ.lab = TRUE, circ.lab.cex = 0.75,
    circ.lab.theta = pi, circ.lab.col = 1, circ.lab.digits = 1,
    circ.lab.offset = 0.025, periph.outside = FALSE,
    periph.outside.offset = 1.2, ...)

Arguments

dat	an input graph.
x	a vector of vertex properties to be plotted (must match the dimensions of dat).
circ.rad	radii at which to draw reference circles.
circ.col	reference circle color.
circ.lwd	reference circle line width.
circ.lty	reference circle line type.
circ.lab	boolean; should circle labels be displayed?
circ.lab.cex	expansion factor for circle labels.
circ.lab.theta	angle at which to draw circle labels.
circ.lab.col	color for circle labels.
circ.lab.digits	digits to display for circle labels.
circ.lab.offset	offset for circle labels.
periph.outside	boolean; should "peripheral" vertices be drawn together beyond the normal vertex radius?
periph.outside.offset	radius at which "peripheral" vertices should be drawn if periph.outside==TRUE.
...	additional arguments to gplot.

Details

gplot.target is a front-end to gplot which implements the target diagram layout of Brandes et al. (2003). This layout seeks to optimize various aesthetic criteria, given the constraint that all vertices lie at fixed radii from the origin (set by x). One important feature of this algorithm is that vertices which belong to mutual dyads (described by Brandes et al. as “core” vertices) are treated differently from vertices which do not (“peripheral” vertices). Layout is optimized for core vertices prior to placing peripheral vertices; thus, the result may be misleading if mutuality is not a salient characteristic of the data.

The layout for gplot.target is handled by gplot.layout.target; additional parameters are specied on the associated manual page. Standard arguments may be passed to gplot, as well.

Value

A two-column matrix of vertex positions (generated by gplot.layout.target)

Author(s)

Carter T. Butts [e-mail]

References

Brandes, U.; Kenis, P.; and Wagner, D. (2003). “Communicating Centrality in Policy Network Drawings.” IEEE Transactions on Visualization and Computer Graphics, 9(2):241-253.

See Also

gplot.layout.target, gplot

Examples

#Generate a random graph
g<-rgraph(15)

#Produce a target diagram, centering by betweenness
gplot.target(g,betweenness(g))

sna documentation built on Sept. 11, 2024, 8:45 p.m.