

   CCoolloorr PPaalleetttteess

        rainbow(n, s = 1, v = 1, start = 0, end = max(1,n - 1)/n, gamma = 1)
        heat.colors(n)
        terrain.colors(n)
        topo.colors(n)
        cm.colors(n)

   AArrgguummeennttss::

          n: the number of colors (>= 1) to be in the palette.

        s,v: the ``saturation'' and ``value'' to be used to
             complete the HSV color descriptions.

      start: the (corrected) hue in [0,1] at which the rainbow
             begins.

        end: the (corrected) hue in [0,1] at which the rainbow
             ends.

      gamma: the gamma correction, see `hsv(.., gamma)'.

   DDeessccrriippttiioonn::

        These functions create a vector of `n' ``contiguous''
        colors.  Conceptually, all of these functions actually
        use (parts of) a line cut out of the 3-dimensional
        color space, parametrized by `hsv(h,s,v, gamma)', where
        `gamma'=1 for the foo`.colors' function, and hence,
        equispaced hues in RGB space tend to cluster at the
        red, green and blue primaries.

        Some applications such as contouring require a palette
        of colors which do not ``wrap around'' to give a final
        color close to the starting one.  With `rainbow', the
        parameters `start' and `end' can be used to specify
        particular subranges of hues.  The following values can
        be used when generating such a subrange: red=0, yel-
        low=1/6, green=2/6, cyan=3/6, blue=4/6 and magenta=5/6.

   VVaalluuee::

        A character vector, `cv', of color names.  This can be
        used either to create a user-defined color palette for
        subsequent graphics by `palette(cv)', a `col=' specifi-
        cation in graphics functions or in `par'.

   SSeeee AAllssoo::

        `colors', `palette',  `hsv', `rgb', `gray'.

   EExxaammpplleess::

        # A Color Wheel
        piechart(rep(1,12), col=rainbow(12))

        ##------ Some palettes ------------
        n <- if(.Device == "postscript") 64 else 16
        ## For screen, larger n may give color allocation problem
        i <- 1:n
        d <- n/20; dy <- 2*d; j <- n%/%4
        plot(i,i+d, type='n', main=paste("color palettes;  n=",n))
        rect(i-.5,     dy, i+.4,   j, col=rainbow(n, start=.7, end=.1))
        text(2*j,    j+dy/4,           "rainbow(n, start=.7, end=.1)")
        rect(i-.5,   j+dy, i+.4, 2*j, col=heat.colors(n))
        text(2*j,  2*j+dy/4,           "heat.colors(n)")
        rect(i-.5, 2*j+dy, i+.4, 3*j, col=terrain.colors(n))
        text(2*j,  3*j+dy/4,           "terrain.colors(n)")
        rect(i-.5, 3*j+dy, i+.4, 4*j, col=topo.colors(n))
        text(2*j,  4*j+dy/4,           "topo.colors(n)")
        rect(i-.5, 3*j+dy, i+.4, 4*j, col=cm.colors(n))
        text(2*j,  4*j+dy/4,           "cm.colors(n)")

