Add Arrows to a Plot
Description
Draw arrows between pairs of points.
Usage
1 2 3 
Arguments
x0, y0 
coordinates of points from which to draw. 
x1, y1 
coordinates of points to which to draw. At least one must the supplied 
length 
length of the edges of the arrow head (in inches). 
angle 
angle from the shaft of the arrow to the edge of the arrow head. 
code 
integer code, determining kind of arrows to be drawn. 
col, lty, lwd 
graphical parameters, possible vectors.

... 
graphical parameters such as 
Details
For each i
, an arrow is drawn between the point (x0[i],
y0[i])
and the point (x1[i], y1[i])
. The coordinate vectors
will be recycled to the length of the longest.
If code = 1
an arrowhead is drawn at (x0[i], y0[i])
and if
code = 2
an arrowhead is drawn at (x1[i], y1[i])
. If
code = 3
a head is drawn at both ends of the arrow. Unless
length = 0
, when no head is drawn.
The graphical parameters col
, lty
and lwd
can be vectors of length greater than one and will be recycled if
necessary.
The direction of a zerolength arrow is indeterminate, and hence so is the direction of the arrowheads. To allow for rounding error, arrowheads are omitted (with a warning) on any arrow of length less than 1/1000 inch.
Note
The first four arguments in the comparable S function are named
x1, y1, x2, y2
.
References
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
See Also
segments
to draw segments.
Examples
1 2 3 4 5 6 7 8  x < stats::runif(12); y < stats::rnorm(12)
i < order(x, y); x < x[i]; y < y[i]
plot(x,y, main = "arrows(.) and segments(.)")
## draw arrows from point to point :
s < seq(length(x)1) # one shorter than data
arrows(x[s], y[s], x[s+1], y[s+1], col = 1:3)
s < s[length(s)]
segments(x[s], y[s], x[s+2], y[s+2], col = "pink")
