Moving average with ghosted lines

moving_average

plot_ma <- function(d, start_lwd=0.9, start_gray=0.5, ...) {
  
  if(!is.data.frame(d))
    d <- as.data.frame(d)
 
  iter <- as.integer(floor(log(nrow(d), base=10)))

  dlwd <- (1.5 - start_lwd) / iter
  dgray <- (0.9 - start_gray) / iter
  pargs <- substitute(...)

  if(ncol(d) >= 2)
    plot(d[,1],d[,2], type="l", lwd=start_lwd, col=gray(start_gray), pargs )
  else
    plot(d[,1], type="l", lwd=start_lwd, col=gray(start_gray), pargs )
  for(i in 1:iter) {
    ma <- function(x,n=10**(i)){filter(x,rep(1/n,n), sides=2)}
    if(ncol(d) >= 2)
      lines(d[,1], ma(d[,2]), col=gray(-i *dgray + start_gray), lwd=(start_lwd + i * dlwd))
    else
      lines(seq(1,nrow(d)), ma(d[,1]), col=gray(-i *dgray + start_gray), lwd=(start_lwd + i * dlwd))
  }
}