adds a circular, self-pointing arrow to a plot

adds a circular arrow, from and to the same point

selfarrow(pos, lwd = 2, lty = 1, lcol = "black", arr.pos = 0.5, 
          path = "L", curve = c(0.1, 0.1), dr = 0.01, code = 1, ...)

Arguments

pos: 2-valued vector with coordinates (x,y) of points *from and to* which to draw arrow.
lwd: line width.
lty: line type.
lcol: line color.
arr.pos: relative position of arrowhead.
path: position of circle: R, L, U, D for right, left, up and down respectively.
curve: relative size of curve (fraction of arrow length).
dr: size of segments, in radians, to draw ellipse (decrease for smoother).
code: how to put the arrowhead.
...: arguments passed to function Arrows.

Value

coordinates (x,y) where arrowhead is drawn

Author

Karline Soetaert <karline.soetaert@nioz.nl>

Details

draws a circular arrow from and to one point

The position of the arrowhead on the circle is set with arr.pos, a value between 0 (at start) and 1(at end of circle)

The type of the arrowhead is set with arr.type which can take the values:

"none" : skips the drawing of arrows.
"simple" : uses comparable R function arrows.
"triangle": uses filled triangle.
"curved" : draws arrowhead with curved edges.
"circle" : draws circular head.
"ellipse" : draws ellepsoid head.
"T" : draws T-shaped (blunt) head.

The size of the arrow head can be specified with the arguments arr.length and arr.width.

See Arrowhead for details on arrow head.

Examples

openplotmat(main = "selfarrow")

pos <- coordinates(3, mx = 0.05)

text(pos, LETTERS[1:3], cex = 2)

for (i in 1:3) 
  selfarrow(pos = pos[i, ], path = "R", arr.pos = 0.2,
            curve = c(0.05, 0.1), lcol = "darkred")

for (i in 1:3) 
  selfarrow(pos = pos[i, ], path = "L", arr.pos = 0.7,
            lcol = "darkblue", curve = c(0.05, 0.05))

for (i in 1:3) 
  selfarrow(pos = pos[i, ], path = "L", arr.pos = 0.5,
            lcol = "darkgreen", code = i, arr.type = "triangle")