[R] fill between lines

[Roger D. Peng]

If one function dominates the other, you can use polygon(),

x <- 1:100
p <- rbind(cbind(x, 0.5*x^2), cbind(rev(x), rev(x^2)))
matplot(x, cbind(x^2, 0.5*x^2), type = "l", col = 1, lty = 1)
polygon(p, col = 2)

or some variant of that.

-roger

ivo welch wrote:
> 
> hi:  is it possible to color areas between two functions?  for example,
> 
>    x<- 1:100;
>    plot(x, x^2, type="l");
>    lines(x,0.5*x^2, type="l");
>    # better
>    plotwithfill(x, x^2, 0.5*x^2, color=c("yellow", "red");
> 
> where the first color is used if f(x)=x^2 > g(x)=0.5*x^2, and the second 
> for the reverse.  Help appreciated.
> 
> Regards, / ivo
> 
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