

   AAdddd AArrrroowwss ttoo aa PPlloott

        arrows(x0, y0, x1, y1, length = 0.25, angle = 30, code = 2,
               col = par("fg"), lty = NULL, xpd = FALSE)
        segments(x0, y0, x1, y1,
               col = par("fg"), lty = par("lty"), xpd = FALSE)

   AArrgguummeennttss::

      x0,y0: coordinates of points from which to draw.

      x1,y1: coordinates of points to which to draw.

     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, xpd: usual graphical parameters as in `par'.

   DDeessccrriippttiioonn::

        `segments' draws a line segment and `arrows' draws an
        arrow between the point `(x0[i], y0[i])' and the point
        `(x1[i],y1[i])'.  If `code=2' an arrowhead is drawn at
        `(x0[i],y0[i])' and if `code=1' an arrowhead is drawn
        at `(x1[i],y1[i])'.  If `code=3' a head is drawn at
        both ends of the arrow.

        The graphical parameters `col' and `lty' can be used to
        specify a color an line texture for the line segments
        which make up the segments or arrows (`col' may be a
        vector).

   SSeeee AAllssoo::

        `polygon' for slightly easier and less flexible line
        drawing and `lines' for the usual polygons.

   EExxaammpplleess::

        x <- runif(12); y <- 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')

