plot-empirical-derivative.R

library(ggplot2)

data(mcycle, package = "MASS")

f_approxfun <- approxfun(mcycle$times, mcycle$accel)
f_splinefun <- splinefun(mcycle$times, mcycle$accel)

mcycle |> 
  ggplot(aes(times, accel)) +
  geom_point() +
  # doesn't work since approxfun() doesn't support derivatives out of the bag,
  # could numDeriv probably
  geom_function(aes(color = "approxfun"), fun = f_approxfun, args = list(deriv = 1)) +
  geom_function(aes(color = "splinefun"), fun = f_splinefun, args = list(deriv = 1)) +
  scale_color_brewer(palette = "Dark2") +
  theme_bw()

# see https://www.andrewheiss.com/blog/2018/02/15/derivatives-r-fun/ for more