colormap_with_level.R

# plotting colormap
xs <- 1:100
ys <- 1:100
zs <- sapply(xs, function (x) { sapply(ys, function (y) { sin(x/(2*pi)) + cos(y/(2*pi)) }) })
z.range <- c(min(zs), max(zs))
default.par <- par(no.readonly=TRUE)
layout(matrix(c(1, 2), 2, 2, byrow=TRUE), c(1, 0.12))
par(mar=c(default.par$mar[1], default.par$mar[2], default.par$mar[3], 1))
image(xs, ys, zs)

# plotting legend
xs.c <- 1
ys.c <- min(zs) + (max(zs) - min(zs)) * 1:100 / 100
zs.c <- matrix(ys.c, 1, 100)
par(mar=c(default.par$mar[1], 0, default.par$mar[3], default.par$mar[4] + 1))
image(xs.c, ys.c, zs.c, axes=FALSE, xlab=NA, ylab=NA)
axis(4)
box()

par(default.par)