library(ggplot2)
set.seed(1)

x <- 1:100
y <- x^2*sin(2*pi*x/100) + 500*rnorm(length(x))

df <- data.frame(x, y)
h <- 12
smoother <- data.frame(ksmooth(x, y, "normal", bandwidth = h, n.points = 100))

ggplot(df, aes(x,y)) + geom_point() + geom_line(data = smoother, aes(x,y))