Coordinate systems

Flipped boxplot

Create a flipped boxplot of fuel economy by transmission type.

► Solution:

ggplot(data = mpg) +
  geom_boxplot(mapping = aes(x = trans, y = hwy)) +
  coord_flip()

Plot highway vs. city fuel economy with an additional geom_abline() layer. How do you set a 45° degree for the diagonal line?

► Solution:

ggplot(data = mpg) +
  geom_jitter(mapping = aes(x = cty, y = hwy)) +
  geom_abline(color = "red")

The coord_fixed() calls fixes the aspect ratio, and also the angle of the red line with slope 1:

ggplot(data = mpg) +
  geom_jitter(mapping = aes(x = cty, y = hwy)) +
  geom_abline(color = "red") +
  coord_fixed()

Try to “estimate” an approximate ratio between the two economy measures by tweaking the slope argument to geom_abline().

► Solution:

Guessing 40 / 30 from the previous plot:

ggplot(data = mpg) +
  geom_jitter(mapping = aes(x = cty, y = hwy)) +
  geom_abline(slope = 40 / 30, color = "red") +
  coord_fixed()