

   LLeevveell ((CCoonnttoouurr)) PPlloottss

        filled.contour(x = seq(0, 1, len = nrow(z)),
                       y = seq(0, 1, len = ncol(z)),
                       z,
                       xlim = range(x, finite=TRUE),
                       ylim = range(y, finite=TRUE),
                       zlim = range(z, finite=TRUE),
                       nlevels = 20,  levels = pretty(zlim, nlevels),
                       color.palette = cm.colors,
                       col = color.palette(length(levels) - 1),
                       plot.title, plot.axes, key.title, key.axes,
                       asp = NA, xaxs="i", yaxs="i", las=1, axes=TRUE, ...)

   AArrgguummeennttss::

        x,y: locations of grid lines at which the values in `z'
             are measured.  These must be in ascending order.
             By default, equally spaced values from 0 to 1 are
             used.  If `x' is a `list', its components `x$x'
             and `x$y' are used for `x' and `y', respectively.
             If the list has component `z' this is used for
             `z'.

          z: a matrix containing the values to be plotted
             (`NA's are allowed).  Note that `x' can be used
             instead of `z' for convenience.

       xlim: x limits for the plot.

       ylim: y limits for the plot.

       zlim: z limits for the plot.

     levels: a set of levels which are used to partition the
             range of `z'.  Areas with `z' values between con-
             secutive levels are painted with the same color.

    nlevels: if `levels' is not specified, the range of `z',
             values is divided into approximately this many
             levels.

   color.palette: a color palette function to be used to assign
             colors in the plot.

        col: an explicit set of colors to be used in the plot.
             This argument overrides any palette function spec-
             ification.

   plot.title: statements which add titles the main plot.

   plot.axes: statements which draw axes on the main plot.
             This overrides the default axes.

   key.title: statements which add titles for the plot key.

   key.axes: statements which draw axes on the plot key.  This
             overrides the default axis.

        asp: the y/x aspect ratio, see `plot.window'.

       xaxs: the x axis style.  The default is to use internal
             labeling.

       yaxs: the y axis style.  The default is to use internal
             labeling.

        las: the style of labeling to be used.  The default is
             to use horizontal labeling.

        ...: additional graphical parameters.

   DDeessccrriippttiioonn::

        This function produces a contour plot with the areas
        between the contours filled in solid color (Cleveland
        calls this a level plot).  A key showing how the colors
        map to z values is shown to the right of the plot.

   NNoottee::

        This function currently uses the `layout' function and
        so is restricted to a full page display.  In future it
        is likely to be replaced by a genuine `levelplot' func-
        tion which will work in multipanel displays.

   AAuutthhoorr((ss))::

        Ross Ihaka.

   RReeffeerreenncceess::

        Cleveland, W. S. (1993).  Visualizing Data, Summit, New
        Jersey: Hobart.

   SSeeee AAllssoo::

        `contour', `image', `palette'.

   EExxaammpplleess::

        data(volcano)
        filled.contour(volcano, color = terrain.colors, asp = 1)# simple

        x <- 10*1:nrow(volcano)
        y <- 10*1:ncol(volcano)
        filled.contour(x, y, volcano, color = terrain.colors,
            plot.title = title(main = "The Topography of Maunga Whau",
            xlab = "Meters North", ylab = "Meters West"),
            plot.axes = { axis(1, seq(100, 800, by = 100))
                          axis(2, seq(100, 600, by = 100)) },
            key.title = title(main="Height (Meters)"),
            key.axes = axis(4, seq(90, 190, by = 10)))# maybe also asp=1
        mtext(paste("filled.contour(.) from", R.version.string),
              side=1, line=4, adj=1, cex=.6)

