adding percentile lines to a density plot [duplicate]

Answer 1

myd = data.frame(xvar=rnorm(2000),yvar=rnorm(2000))

    xd <- data.frame(density(myd$xvar)[c("x", "y")])
    p <- ggplot(xd, aes(x, y)) + 

      geom_area(data = subset(xd, x < -1), fill = "pink") +
      geom_area(data = subset(xd, x < -1.96), fill = "red") +
      geom_area(data = subset(xd, x > 1), fill = "lightgreen") +
      geom_area(data = subset(xd, x > 1.96), fill = "green") +

      geom_line()

    p