filled.contour             package:base             R Documentation

Level (Contour) Plots

Description:

     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.

Usage:

     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),
                    levels = pretty(zlim, nlevels), nlevels = 20,
                    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,
                    ...)

Arguments:

     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'.
           Must be strictly increasing (and finite).  Areas with `z'
          values between consecutive 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 specification.

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. 

axes, ...: additional graphical parameters.

Note:

     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' function which will work in
     multipanel displays.

     The ouput produced by `filled.contour' is actually a combination
     of two plots; one is the filled contour and one is the legend. Two
     separate coordinate systems are set up for these two plots, but
     they are only used internally - once the function has returned
     these coordinate systems are lost.  If you want to annotate the
     main contour plot, for example to add points, you can specify
     graphics commands in the plot.axes argument.  An example is given
     below.

Author(s):

     Ross Ihaka.

References:

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

See Also:

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

Examples:

     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\n(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 = .66)

     # Annotating a filled contour plot
     a <- expand.grid(1:20, 1:20)
     b <- matrix(a[,1] + a[,2], 20)
     filled.contour(x = 1:20, y = 1:20, z = b,
                    plot.axes={ axis(1); axis(2); points(10,10) })

