expand_axis.R

# the first argument gives expansion equal to its multiplication by limit range;
ggplot(mpg, aes(displ, hwy)) +
  geom_point() +
  scale_x_continuous(limits = c(1, 7), expand = c(.1, 0))
# right position will be 7 + (7-1) * .1 = 7.6

# the second gives the absolute expansion added to both end of the axis:
ggplot(mpg, aes(displ, hwy)) +
  geom_point() +
  scale_x_continuous(limits = c(1, 7), expand = c(0, 1))
# right position will be 7 + 1 = 8