R: Generate a smoothly varying set of colors

colorpanel {gplots} | R Documentation

## Generate a smoothly varying set of colors

### Description

`colorpanel` generate a set of colors that varies smoothly. `redgreen`, `greenred`, `bluered`, and `redblue` generate red-black-green, green-black-red, red-white-blue, and blue-white-red colorbars, respectively. colors

### Usage

    colorpanel(n, low, mid, high)
    redgreen(n)
    greenred(n)
    bluered(n)
    redblue(n)

### Arguments

`n` | Desired number of color elements in the panel.
`low, mid, high` | Colors to use for the Lowest, middle, and highest values. `mid` may be ommited.

### Details

The values for `low, mid, high` can be given as color names ('red'), plot color index (2=red), and HTML-style RGB, ("\#FF0000"=red).

If `mid` is supplied, then the returned color panel will consist of `n - floor(n/2)` HTML-style RGB elements which vary smoothly between `low` and `mid`, then between `mid` and `high`. Note that if `n` is even, the color `mid` will occur twice at the center of the sequence.

If `mid` is omitted, the color panel will vary smoothly beween `low` and `high`.

### Value

Vector of HTML-style RGB colors.

### Author(s)

Gregory R. Warnes greg@warnes.net

### See Also

`colors`

### Examples

    showpanel <- function(col)
    {
      image(z=matrix(1:100, ncol=1), col=col, xaxt="n", yaxt="n" )
    }

    par(mfrow=c(3,3))

    # two colors only:
    showpanel(colorpanel(8,low="red",high="green"))

    # three colors
    showpanel(colorpanel(8,"red","black","green"))
    # note the duplicatation of black at the center, using an odd
    # number of elements resolves this:
    showpanel(colorpanel(9,"red","black","green"))

    showpanel(greenred(64))
    showpanel(redgreen(64))
    showpanel(bluered(64))
    showpanel(redblue(64))

[Package gplots version 3.0.1 Index]