Handy function for HSV-scale-izing real-valued data.

hsv_scale.R

hsv.scale <- function (var, hmin, hmax=hmin, smin=1, smax=smin, vmin=1, vmax=vmin,
                       na.col=rgb(0.75, 0.75, 0.75))
{
    var.min <- min(var, na.rm=TRUE)
    var.max <- max(var, na.rm=TRUE)
    h.f <- approxfun(c(var.min, var.max), c(hmin, hmax))
    s.f <- approxfun(c(var.min, var.max), c(smin, smax))
    v.f <- approxfun(c(var.min, var.max), c(vmin, vmax))

    tmp <- var
    tmp[is.na(var)] <- var.min
    col <- hsv(h=h.f(tmp), s=s.f(tmp), v=v.f(tmp))
    col[is.na(var)] <- na.col

    col
}