Arrows: adds arrows with improved arrowhead to a plot

Description

adds one or more arrows to a plot; arrowhead shape is either curved, a triangle, a circle or simple

Usage

Arrows(x0, y0, x1, y1, code = 2, arr.length = 0.4, 
  arr.width = arr.length/2, arr.adj = 0.5, arr.type = "curved",
  segment = TRUE, col = "black", lcol = col, lty = 1, arr.col = lcol, 
  lwd = 1, arr.lwd = lwd, ...)

Arguments

x0: x-coordinates of points *from* which to draw arrows; either one value or a vector.
y0: y-coordinates of points *from* which to draw arrows; either one value or a vector.
x1: x-coordinates of points *to* which to draw arrows; either one value or a vector.
y1: y-coordinates of points *to* which to draw arrows; either one value or a vector.
code: integer code determining kind of arrows to draw.
arr.length: approximate length of arrowhead, in cm; either one value or a vector.
arr.width: approximate width of arrowhead, in cm; either one value or a vector.
arr.adj: 0,0.5,1 specifying the adjustment of the arrowhead.
arr.type: type of arrowhead to draw, one of "none", "simple", "curved", "triangle", "circle", "ellipse" or "T".
segment: logical specifying whether or not to draw line segments.
col: general line color specification; one value or a vector.
lcol: line color specifications; either one value or a vector. ignored when arr.type = "simple" or "T" - use "col"
lty: line type specifications; either one value or a vector.
arr.col: color of arrowhead; either one value or a vector.
lwd: general line width specification. The default value changed to 1 from version 1.4 (was 2)
arr.lwd: line width of arrowhead.
...: arguments passed to lines, segments or Arrowhead function.

Author

Karline Soetaert <karline.soetaert@nioz.nl>

Details

x0, y0, x1, y1, arr.length, arr.width, arr.adj, lcol, lty and arr.col can be a vector, of the same length.

For each 'i', an arrow is drawn between the point '(x0[i], y0[i])' and the point '(x1[i],y1[i])'.

If code=1 an arrowhead is drawn at '(x0[i],y0[i])'
if code=2 an arrowhead is drawn at '(x1[i],y1[i])'.
If code=3 an arrowhead is drawn at both ends of the arrow
unless arr.length = 0, when no head is drawn.

If arr.adj = 0.5 then the centre of the arrowhead is at the point at which it is drawn.
arr.adj = 1 causes the tip of the arrowhead to touch the point.
arr.adj = 2 causes the base of the arrowhead to touch the point.

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

"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

Examples

Run this code

xlim <- c(-5 , 5)
ylim <- c(-10, 10)
plot(0, type = "n", xlim = xlim, ylim = ylim, 
     main = "Arrows,  type = 'curved'")
x0 <- runif(100, xlim[1], xlim[2])
y0 <- runif(100, ylim[1], ylim[2])
x1 <- x0+runif(100, -1, 1)
y1 <- y0+runif(100, -1, 1)
Arrows(x0, y0, x1, y1, arr.length = runif(100), code = 2, 
       arr.type = "curved", arr.col = 1:100, lcol = 1:100)
  
plot(0, type = "n", xlim = xlim, ylim = ylim, 
     main = "Arrows,  type = 'circle'")
x0 <- runif(100, xlim[1], xlim[2])
y0 <- runif(100, ylim[1], ylim[2])
x1 <- x0 + runif(100, -1, 1)
y1 <- y0 + runif(100, -1, 1)
Arrows(x0, y0, x1, y1, arr.length = 0.2, code = 3, 
       arr.type = "circle", arr.col = "grey")
  
plot(0, type = "n", xlim = xlim, ylim = ylim, 
     main = "Arrows,  type = 'ellipse'")
Arrows(x0, y0, x1, y1, arr.length = 0.2, arr.width = 0.5, 
       code = 3, arr.type = "ellipse",  arr.col = "grey")

curve(expr = sin(x), 0, 2*pi+0.25, main = "Arrows")
x  <- seq(0, 2*pi, length.out = 10)
xd <- x + 0.025
Arrows(x, sin(x), xd, sin(xd), type = "triangle", 
       arr.length = 0.5, segment = FALSE)
  
xx <- seq(0, 10*pi, length.out = 1000)
plot(sin(xx)*xx, cos(xx)*xx, type = "l", axes = FALSE, 
     xlab = "", ylab = "", main = "Arrows,  type = 'curved'")
x  <- seq(0, 10*pi, length.out = 20)
x1 <- sin(x)*x
y1 <- cos(x)*x
xd <- x+0.01
x2 <- sin(xd)*xd
y2 <- cos(xd)*xd
Arrows(x1, y1, x2, y2, arr.type = "curved", arr.length = 0.4, 
       segment = FALSE, code = 1, arr.adj = 0.5 )

plot(sin(xx)*xx, cos(xx)*xx, type = "l", axes = FALSE, 
     xlab = "", ylab = "", main = "Arrows,  type = 'T'")
Arrows(x1, y1, x2, y2, arr.type = "T", arr.length = 0.4, 
       code = 1, arr.lwd = 2)


# arguments passed to polygon:

xlim <- c(-5 , 5)
ylim <- c(-10, 10)
plot(0, type = "n", xlim = xlim, ylim = ylim, 
     main = "Arrows,  type = 'curved'")
x0 <- runif(100, xlim[1]-1, xlim[2]+0.5)  # exceeds the x-range
y0 <- runif(100, ylim[1], ylim[2])
x1 <- x0+runif(100, -1, 1)
y1 <- y0+runif(100, -1, 1)
Arrows(x0, y0, x1, y1, arr.length = runif(100), code = 2, 
       arr.type = "curved", arr.col = 1:100, lcol = 1:100, xpd = TRUE)

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