network.loop: Add Loops to a Plot

In network: Classes for Relational Data

Add Loops to a Plot

Description

network.loop draws a "loop" at a specified location; this is used to designate self-ties in plot.network.

Usage

network.loop(
  x0,
  y0,
  length = 0.1,
  angle = 10,
  width = 0.01,
  col = 1,
  border = 1,
  lty = 1,
  offset = 0,
  edge.steps = 10,
  radius = 1,
  arrowhead = TRUE,
  xctr = 0,
  yctr = 0,
  ...
)

Arguments

x0	a vector of x coordinates for points of origin.
y0	a vector of y coordinates for points of origin.
length	arrowhead length, in current plotting units.
angle	arrowhead angle (in degrees).
width	width for loop body, in current plotting units (can be a vector).
col	loop body color (can be a vector).
border	loop border color (can be a vector).
lty	loop border line type (can be a vector).
offset	offset for origin point (can be a vector).
edge.steps	number of steps to use in approximating curves.
radius	loop radius (can be a vector).
arrowhead	boolean; should arrowheads be used? (Can be a vector.)
xctr	x coordinate for the central location away from which loops should be oriented.
yctr	y coordinate for the central location away from which loops should be oriented.
...	additional arguments to polygon.

Details

network.loop is the companion to network.arrow; like the latter, plot elements produced by network.loop are drawn using polygon, and as such are scaled based on the current plotting device. By default, loops are drawn so as to encompass a circular region of radius radius, whose center is offset units from x0,y0 and at maximum distance from xctr,yctr. This is useful for functions like plot.network, which need to draw loops incident to vertices of varying radii.

Value

None.

Note

network.loop is a direct adaptation of gplot.loop, from the sna package.

Author(s)

Carter T. Butts [e-mail]

See Also

network.arrow, plot.network, polygon

Examples

#Plot a few polygons with loops
plot(0,0,type="n",xlim=c(-2,2),ylim=c(-2,2),asp=1)
network.loop(c(0,0),c(1,-1),col=c(3,2),width=0.05,length=0.4,
  offset=sqrt(2)/4,angle=20,radius=0.5,edge.steps=50,arrowhead=TRUE)
polygon(c(0.25,-0.25,-0.25,0.25,NA,0.25,-0.25,-0.25,0.25), 
    c(1.25,1.25,0.75,0.75,NA,-1.25,-1.25,-0.75,-0.75),col=c(2,3))

network documentation built on April 3, 2025, 10:02 p.m.