Adding a point based on data to ggplot

Question

I have this issue where I have to add a "target" point to an existing plot, based on a value in the data.

For example, in the reprex - to make a point at (2010, 605). (target year, 110% of 2008 profit)

I know I can calculate before plotting ... but is there a way using that .data pronoun to get the profit for 2008 within the ggplot?

Reprex:

library(ggplot2)

sales <- data.frame(
  year = c(2005, 2006, 2007, 2008),
  profit = c(340, 500, 600, 550)
)

sales %>% 
  ggplot() +
  aes(x = year, y = profit) +
  geom_line() +
# throws error: Error: Discrete value supplied to continuous scale
  geom_point(aes(x = 2010, y = .data[["year"]] == 2008))


# calculate before plot
pull(sales[sales[["year"]] == 2008, ]["profit"])

Answer 1

You can use :

library(ggplot2)

ggplot(sales) + aes(x = year, y = profit) +
  geom_line() + 
  geom_point(aes(x = 2010, y = .data[['profit']][.data[["year"]] == 2008]))