color scale in R

require(graphics)
# A Color Wheel
pie(rep(1,12), col=rainbow(12))



##------ Some palettes ------------##
n = 32;
main.name = paste("color palettes; n=",n)
ch.col = c("rainbow(n, start=.7, end=.1)", "heat.colors(n)", "terrain.colors(n)", "topo.colors(n)", "cm.colors(n)");

nt <- length(ch.col)
i <- 1:n;
j <- n/nt;
d <- j/6;
dy <- 2*d;

plot(i,i+d, type="n", yaxt="n", xaxt="n", ylab="", , xlab ="", main=main.name) #yaxt="n" set no y axie label and tick.
for (k in 1:nt) {
rect(i-.5, (k-1)*j+ dy, i+.4, k*j, col = eval(parse(text=ch.col[k])), border = "grey");
text(2.5*j, k * j + dy/2, ch.col[k])
}