gplot.arrow: Add Arrows or Segments to a Plot

In sna: Tools for Social Network Analysis

Add Arrows or Segments to a Plot

Description

gplot.arrow draws a segment or arrow between two pairs of points; unlike arrows or segments, the new plot element is drawn as a polygon.

Usage

gplot.arrow(x0, y0, x1, y1, length = 0.1, angle = 20, width = 0.01,
    col = 1, border = 1, lty = 1, offset.head = 0, offset.tail = 0,
    arrowhead = TRUE, curve = 0, edge.steps = 50, ...)

Arguments

x0	A vector of x coordinates for points of origin
y0	A vector of y coordinates for points of origin
x1	A vector of x coordinates for destination points
y1	A vector of y coordinates for destination points
length	Arrowhead length, in current plotting units
angle	Arrowhead angle (in degrees)
width	Width for arrow body, in current plotting units (can be a vector)
col	Arrow body color (can be a vector)
border	Arrow border color (can be a vector)
lty	Arrow border line type (can be a vector)
offset.head	Offset for destination point (can be a vector)
offset.tail	Offset for origin point (can be a vector)
arrowhead	Boolean; should arrowheads be used? (Can be a vector))
curve	Degree of edge curvature (if any), in current plotting units (can be a vector)
edge.steps	For curved edges, the number of steps to use in approximating the curve (can be a vector)
...	Additional arguments to polygon

Details

gplot.arrow provides a useful extension of segments and arrows when fine control is needed over the resulting display. (The results also look better.) Note that edge curvature is quadratic, with curve providing the maximum horizontal deviation of the edge (left-handed). Head/tail offsets are used to adjust the end/start points of an edge, relative to the baseline coordinates; these are useful for functions like gplot, which need to draw edges incident to vertices of varying radii.

Value

None.

Author(s)

Carter T. Butts [e-mail]

See Also

gplot, gplot.loop, polygon

Examples

  #Plot two points
  plot(1:2,1:2)
  
  #Add an edge
  gplot.arrow(1,1,2,2,width=0.01,col="red",border="black")

sna documentation built on Feb. 16, 2023, 9:52 p.m.