[R] creating rainbow gradients

[Duncan Murdoch]

On 17/09/2008 4:58 PM, Gillian Silver wrote:
> Hi, how can I create a rainbow gradient in R? For example, let's say I have
> a plot of y = x...and I want the plot to go from red -> orange -> yellow ->
> green -> blue -> etc.
> Right now, I know how to do something like go from red to blue, using the
> plotrix library:
> 
> library(plotrix)
> redToBlue <-
> color.scale(x,redrange=c(0,1),greenrange=c(0,1),bluerange=c(0,1),extremes=c("red","blue"))
> plot(x, y, col=redToBlue)
> 
> But I can't figure out how to make the colors a rainbow. (I don't understand
> how the redrange, greenrange, and bluerange parameters in color.scale work.)
> 
> Could someone please help?

Others have pointed you to the rainbow() function; you should also look 
at colorRamp, in case you want to construct your own colour sequence.

Duncan Murdoch