grid.lines               package:grid               R Documentation

Draw Lines in a Grid Viewport

Description:

     These functions create and draw a series of lines.

Usage:

     grid.lines(x = unit(c(0, 1), "npc"),
               y = unit(c(0, 1), "npc"), 
               default.units = "npc", 
               arrow = NULL, name = NULL,
               gp=gpar(), draw = TRUE, vp = NULL)
     linesGrob(x = unit(c(0, 1), "npc"),
               y = unit(c(0, 1), "npc"), 
               default.units = "npc", 
               arrow = NULL, name = NULL,
               gp=gpar(), vp = NULL)
     grid.polyline(...)
     polylineGrob(x = unit(c(0, 1), "npc"),
                  y = unit(c(0, 1), "npc"), 
                  id=NULL, id.lengths=NULL,
                  default.units = "npc", 
                  arrow = NULL, name = NULL,
                  gp=gpar(), vp = NULL)

Arguments:

       x: A numeric vector or unit object specifying x-values.

       y: A numeric vector or unit object specifying y-values.

default.units: A string indicating the default units to use if 'x' or
          'y' are only given as numeric vectors.

   arrow: A list describing arrow heads to place at either end of the
          line, as produced by the 'arrow' function.

    name: A character identifier. 

      gp: An object of class 'gpar', typically the output from a call
          to the function 'gpar'.  This is basically a list of
          graphical parameter settings.

    draw: A logical value indicating whether graphics output should be
          produced.

      vp: A Grid viewport object (or NULL).

      id: A numeric vector used to separate locations in 'x' and 'y'
          into multiple lines.  All locations with the same 'id' belong
          to the same line.

id.lengths: A numeric vector used to separate locations in 'x' and 'y'
          into multiple lines.  Specifies consecutive blocks of
          locations which make up separate lines.

     ...: Arguments passed to 'polylineGrob'.

Details:

     The first two functions create a lines grob (a graphical object
     describing lines), and 'grid.lines' draws the lines (if 'draw' is
     'TRUE').

     The second two functions create or draw a polyline grob, which is
     just like a lines grob, except that there can be multiple distinct
     lines drawn.

Value:

     A lines grob or a polyline grob. 'grid.lines' returns a lines grob
     invisibly.

Author(s):

     Paul Murrell

See Also:

     Grid, 'viewport', 'arrow'

Examples:

     grid.lines()
     # Using id (NOTE: locations are not in consecutive blocks)
     grid.newpage()
     grid.polyline(x=c((0:4)/10, rep(.5, 5), (10:6)/10, rep(.5, 5)),
                  y=c(rep(.5, 5), (10:6/10), rep(.5, 5), (0:4)/10),
                  id=rep(1:5, 4),
                  gp=gpar(col=1:5, lwd=3))
     # Using id.lengths
     grid.newpage()
     grid.polyline(x=outer(c(0, .5, 1, .5), 5:1/5),
                  y=outer(c(.5, 1, .5, 0), 5:1/5),
                  id.lengths=rep(4, 5),
                  gp=gpar(col=1:5, lwd=3))

