set upper limit in ggplot to include label greater than the maximum value

Question

My data range always seems to be greater than the top label in the y-axis. Is there a way I can automatically include it without manually setting limits?

e.g. in

Answer 1

dat<-data.frame(x=1:10, y=c(11:17,5:3))
ggplot(dat, aes(x,y)) + 
  geom_point()+
  scale_y_continuous(breaks=c(pretty(dat$y, n=4),18), expand=c(0.25, 0.25))

The pretty function chooses nice breaks as 1, 2 or 5 times a power of 10. Then I just included 18 to that vector.