R gist — Plotting the area under the curve with ggplot

knitr::opts_chunk$set(echo = TRUE)
library(tidyverse)
library(ggthemr)
ggthemr("earth")

x <- 1:11
y <- (1.5:11.5)^2
low <- (0:10)^2
upp <- (3:13)^2

ggplot() +
  aes(x, y) +
  geom_line() +
  geom_ribbon(aes(ymin = low, ymax = upp), alpha = 0.5)

x2 <- c(1:8, NA, NA, NA)
ggplot() +
  aes(x, y) +
  geom_line() +
  geom_ribbon(aes(x = x2, ymin = low, ymax = upp), alpha = 0.5)

x <- seq(-4, 4, by = 0.05)
y <- dnorm(x)

p <- ggplot() +
  aes(x, y) +
  geom_line()
p

p +
  geom_ribbon(
    aes(x = ifelse(x <= -1 , x, NA), ymin = 0, ymax = y),
    fill = "#E84646",
    alpha = 0.4
  )