shaded area between two lines in ggplot

October 28, 2022

I would like to create a shaded area in color blue between the two dotted lines (-0.5 and 0.5), tried with geom_polygon() but didn’t work.
How can this be done in the best possible way?

model <- lm(Sepal.Width ~ Petal.Length, data = iris)

ggplot(data.frame(x = seq(model$residuals), y = model$residuals)) +
  geom_point(aes(x, y)) +
  
  geom_hline(yintercept = 0, linetype = "dashed") +

  geom_hline(yintercept = 0.5, linetype = "dotted") +
  

  geom_hline(yintercept = -0.5, linetype = "dotted") +
  
  
  labs(x = "Index", y = "Residuals", 
       title = paste("Residuals of", format(model$call)))

>Solution :

With annotate:

annotate("rect", xmin = -Inf, xmax = Inf, ymin = -0.5, ymax = 0.5, alpha = .2, fill = "blue")

Output:

ggplot(data.frame(x = seq(model$residuals), y = model$residuals)) +
  geom_point(aes(x, y)) +
  geom_hline(yintercept = 0, linetype = "dashed") +
  geom_hline(yintercept = c(-0.5, 0.5), linetype = "dotted") +
  annotate("rect", xmin = -Inf, xmax = Inf, ymin = -0.5, ymax = 0.5, alpha = .2, fill = "blue") +
  labs(x = "Index", y = "Residuals", 
       title = paste("Residuals of", format(model$call)))