

   Palettes {base}                              R Documentation

   CCoolloorr PPaalleetttteess

   DDeessccrriippttiioonn::

        These functions create a vector of `n' ``contiguous''
        colors.

   UUssaaggee::

        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)

   AArrgguummeennttss::

          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)'.

   DDeettaaiillss::

        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 fol-
        lowing values can be used when generating such a sub-
        range: red=0, yellow=1/6, green=2/6, cyan=3/6, blue=4/6
        and magenta=5/6.

   VVaalluuee::

        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'.

   SSeeee AAllssoo::

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

   EExxaammpplleess::

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

        ##------ Some palettes ------------
        ch.col <- c("rainbow(n, start=.7, end=.1)", "heat.colors(n)",
                    "terrain.colors(n)", "topo.colors(n)", "cm.colors(n)")

        n <- if(.Device == "postscript") 64 else 16
             # Since for screen, larger n may give color allocation problem
        nt <- length(ch.col)
        i <- 1:n; j <- n / nt; d <- j/6; dy <- 2*d
        plot(i,i+d, type="n", yaxt="n", ylab="", main=paste("color palettes;  n=",n))
        for (k in 1:nt) {
          rect(i-.5,(k-1)*j+ dy, i+.4,  k*j, col=eval(parse(text=ch.col[k])))
          text(2*j,  k * j +dy/4, ch.col[k])
        }

