I’ve put together this graph and I would like to be able to add a legend to it but can’t seem to figure out why it’s not showing up and how to easily add it.

data <- data.frame(group = LETTERS[1:5],    # Create example data
                   pol_nb = c(1000, 800, 1200, 900, 800),
                   Prediction = c(0.6, 0.9, 0.9, 0.5, 0.8),
                   Actual = c(0.5, 1.0, 1.2, 1.5, 0.9))
buffer <- 0.5
scale <- max(data$Prediction)/max(data$pol_nb)
total <- sum(data$pol_nb)

ggplot(data) +
  ### add model fitted prediction
  geom_point(aes(x = group, y = Prediction), group = 1, shape = 21, size = 3, color = "black", fill = "green3") +
  geom_line(aes(x = group, y = Prediction), group = 1, color = "green3") +
  
  ### add actual average
  geom_point(aes(x = group, y = Actual), group = 1, shape = 22, size = 3, color = "black", fill = "purple") +
  geom_line(aes(x = group, y = Actual), group = 1, color = "purple") +
  
  ### add bars
  geom_col(aes(x = group, y = pol_nb * buffer * scale), color = "black", fill = "gold", width = 0.5) + 
  scale_y_continuous(
    name = "Prediction",
    sec.axis = sec_axis(~ ./ (buffer * scale * total), 
                        name = 'PoliciesDistribution',
                        labels = scales::label_percent())) +

  theme_light()

I’ve figured out from this threadif you put the color inside of the aes() that it does appear but not in the way I would expect.