screen               package:graphics               R Documentation

Creating and Controlling Multiple Screens on a Single Device

Description:

     'split.screen' defines a number of regions within the current
     device which can, to some extent, be treated as separate graphics
     devices.  It is useful for generating multiple plots on a single
     device.  Screens can themselves be split, allowing for quite
     complex arrangements of plots.

     'screen' is used to select which screen to draw in.

     'erase.screen' is used to clear a single screen, which it does by
     filling with the background colour.

     'close.screen' removes the specified screen definition(s).

Usage:

     split.screen(figs, screen, erase = TRUE)
     screen(n = , new = TRUE)
     erase.screen(n = )
     close.screen(n, all.screens = FALSE)

Arguments:

    figs: A two-element vector describing the number of rows and the
          number of columns in a screen matrix _or_ a matrix with 4
          columns. If a matrix, then each row describes a screen with
          values for the left, right, bottom, and top of the screen (in
          that order) in NDC units, that is 0 at the lower left coner
          of the device surface, and 1 at the upper right corner.

  screen: A number giving the screen to be split.  It defaults to the
          current screen if there is one, otherwise the whole device
          region.

   erase: logical: should be selected screen be cleared?

       n: A number indicating which screen to prepare for drawing
          ('screen'), erase ('erase.screen'), or close
          ('close.screen').  ('close.screen' will accept a vector of
          screen numbers.)

     new: A logical value indicating whether the screen should be
          erased as part of the preparation for drawing in the screen.

all.screens: A logical value indicating whether all of the screens
          should be closed.

Details:

     The first call to 'split.screen' places R into split-screen mode. 
     The other split-screen functions only work within this mode. While
     in this mode, certain other commands should be avoided (see the
     Warnings section below).  Split-screen mode is exited by the
     command 'close.screen(all = TRUE)'.

     If the current screen is closed, 'close.screen' sets the current
     screen to be the next larger screen number if there is one,
     otherwise to the first available screen.

Value:

     'split.screen' returns a vector of screen numbers for the
     newly-created screens.  With no arguments, 'split.screen' returns
     a vector of valid screen numbers.

     'screen' invisibly returns the number of the selected screen. With
     no arguments, 'screen' returns the number of the current screen.

     'close.screen' returns a vector of valid screen numbers.

     'screen', 'erase.screen', and 'close.screen' all return 'FALSE' if
     R is not in split-screen mode.

Warnings:

     The recommended way to use these functions is to completely draw a
     plot and all additions (ie. points and lines) to the base plot,
     prior to selecting and plotting on another screen. The behavior
     associated with returning to a screen to add to an existing plot
     is unpredictable and may result in problems that are not readily
     visible.

     These functions are totally incompatible with the other mechanisms
     for arranging plots on a device: 'par(mfrow)', 'par(mfcol)' and
     'layout()'.

     The functions are also incompatible with some plotting functions,
     such as 'coplot', which make use of these other mechanisms.

     'erase.screen' will appear not to work if the background colour is
     transparent (as it is by default on most devices).

References:

     Chambers, J. M. and Hastie, T. J. (1992) _Statistical Models in
     S_. Wadsworth & Brooks/Cole.

See Also:

     'par', 'layout', 'Devices', 'dev.*'

Examples:

     if (interactive()) {
     par(bg = "white")           # default is likely to be transparent
     split.screen(c(2,1))        # split display into two screens
     split.screen(c(1,3), screen = 2) # now split the bottom half into 3
     screen(1) # prepare screen 1 for output
     plot(10:1)
     screen(4) # prepare screen 4 for output
     plot(10:1)
     close.screen(all = TRUE)    # exit split-screen mode

     split.screen(c(2,1))        # split display into two screens
     split.screen(c(1,2),2)      # split bottom half in two
     plot(1:10)                  # screen 3 is active, draw plot
     erase.screen()              # forgot label, erase and redraw
     plot(1:10, ylab= "ylab 3")
     screen(1)                   # prepare screen 1 for output
     plot(1:10)
     screen(4)                   # prepare screen 4 for output
     plot(1:10, ylab="ylab 4")
     screen(1, FALSE)            # return to screen 1, but do not clear
     plot(10:1, axes=FALSE, lty=2, ylab="")  # overlay second plot
     axis(4)                     # add tic marks to right-hand axis
     title("Plot 1")
     close.screen(all = TRUE)    # exit split-screen mode
     }

