

   SSeett uupp WWoorrlldd CCoooorrddiinnaatteess ffoorr GGrraapphhiiccss WWiinnddooww

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

   AArrgguummeennttss::

   xlim, ylim: numeric of length 2, giving the x and y coordi-
             nates ranges.

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

        asp: numeric, giving the aspect ratio y/x.

        ...: further graphical parameters as in `par(..)'.

   DDeessccrriippttiioonn::

        This function sets up the world coordinate system for a
        graphics window.  It is called by higher level func-
        tions such as `plot.default' (after `plot.new').

   DDeettaaiillss::

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

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

        Usually, one should rather use the higher level func-
        tions such as `plot', `hist', `image', ..., instead and
        refer to their help pages for explanation of the argu-
        ments.

   SSeeee AAllssoo::

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

   EExxaammpplleess::

        ##--- An example for the use of  `asp' :
        library(mva)
        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=0.5)

