But that just draws 3 separate plots. My main problem was the derivative, not so much the plotting (or maybe it was 'plotting an arbitrary function'); but I lo

But that just draws 3 separate plots. My main problem was the derivative, not so much the plotting (or maybe it was 'plotting an arbitrary function'); but I looked it up and it seems I slightly misremembered what it was I wanted to do. I wanted to draw a cubic spline, not a sine. What I ended up doing was spline_x <- 1:6 spline_y <- c(0, 0.5, 2, 2, 0.5, 0) spl_fun <- splinefun(spline_x, spline_y) p <- ggplot(data.frame(x=spline_x, y=spline_y), aes(x, y)) p <- p + stat_function(fun = spl_fun) p <- p + stat_function(fun = spl_fun, arg = list(deriv = 2)) I still don't quite understand how that derivative works - ?list doesn't mention anything about 'deriv', and there's a function called 'deriv' but I'm not sure how that's being interpreted in the code above. Also it seems recent versions of ggplot2 have geom_xspline() which does what I need (I'm told) but that wasn't in the release version when I was doing it.