| arrow {grid} | R Documentation | 
Produces a description of what arrows to add to a line.
The result can be passed to a function that draws a line,
e.g., grid.lines.
arrow(angle = 30, length = unit(0.25, "inches"),
      ends = "last", type = "open")
angle | 
 The angle of the arrow head in degrees (smaller numbers produce narrower, pointier arrows). Essentially describes the width of the arrow head.  | 
length | 
 A unit specifying the length of the arrow head (from tip to base).  | 
ends | 
 One of   | 
type | 
 One of   | 
arrow()