plot.window             package:graphics             R Documentation

Set up World Coordinates for Graphics Window

Description:

     This function sets up the world coordinate system for a graphics
     window.  It is called by higher level functions such as
     'plot.default' (_after_ 'plot.new').

Usage:

     plot.window(xlim, ylim, log = "", asp = NA, ...)

Arguments:

xlim, ylim: numeric of length 2, giving the x and y coordinates ranges.

     log: character; indicating which axes should be in log scale.

     asp: numeric, giving the *asp*ect ratio y/x.

     ...: further graphical parameters as in 'par'.

Details:

     Note that if 'asp' is a finite positive value then the window is
     set up so that one data unit in the x direction is equal in length
     to 'asp' * one data unit in the y direction.

     The special case 'asp == 1' produces plots where distances between
     points are represented accurately on screen.  Values with 'asp >
     1' can be used to produce more accurate maps when using latitude
     and longitude.

     The function attempts to produce a plausible set of scales if one
     or both of 'xlim' and 'ylim' is of length one or the two values
     given are identical, but it is better to avoid that case.

     Usually, one should rather use the higher level functions such as
     'plot', 'hist', 'image', ..., instead and refer to their help
     pages for explanation of the arguments.

See Also:

     'xy.coords', 'plot.xy', 'plot.default'.

Examples:

     ##--- An example for the use of 'asp' :
     library(stats)  # normally loaded
     data(eurodist)
     loc <- cmdscale(eurodist)
     rx <- range(x <- loc[,1])
     ry <- range(y <- -loc[,2])
     plot(x, y, type="n", asp=1, xlab="", ylab="")
     abline(h = pretty(rx, 10), v = pretty(ry, 10), col = "lightgray")
     text(x, y, names(eurodist), cex=0.8)

