to create a distortion in a time series

distort.R

#' function that distorts
distort <- function(y, from, to){
  before <- seq(from=1, to=from,length.out  = to)
  after <- seq(from=from+1, to=length(y), length.out  = length(y)-to)
  out <- approx(seq(y),y, xout = c(before, after))
  return(out$y)
}

# example
x <- seq(1,120, by = 1)
y <- seq(x)*sin(x/2)
plot(x, y, type="l")
lines(x, distort(y, 60, 20), col = "red")