grid.xaxis               package:grid               R Documentation

Draw an X-Axis

Description:

     These functions create and draw an x-axis.

Usage:

     grid.xaxis(at = NULL, label = TRUE, main = TRUE, name = NULL, gp = gpar(),
                draw = TRUE, vp = NULL)
     xaxisGrob(at = NULL, label = TRUE, main = TRUE, name = NULL, gp = gpar(),
              vp = NULL)

Arguments:

      at: A numeric vector of x-value locations for the tick marks.

   label: A logical value indicating whether to draw the labels on the
          tick marks.

    main: A logical value indicating whether to draw the axis at the
          bottom ('TRUE') or at the top ('FALSE') of the viewport.

    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 obect (or 'NULL').

Details:

     Both functions create an xaxis grob (a graphical object describing
     an xaxis), but only 'grid.xaxis' draws the xaxis (and then only if
     'draw' is 'TRUE').

Value:

     An xaxis grob.  'grid.xaxis' returns the value invisibly.

Children:

     If the 'at' slot of an xaxis grob is not 'NULL' then the xaxis
     will have the following children:

     major representing the line at the base of the tick marks.

     ticks representing the tick marks.

     labels representing the tick labels.

     If the 'at' slot is 'NULL' then there are no children and ticks
     are drawn based on the current viewport scale.

Author(s):

     Paul Murrell

See Also:

     Grid, 'viewport', 'grid.yaxis'

