3.10 Exercise solutions

3.10.1 Exercise 1

• What geoms would you use to draw each of the following named plots?
  • scatterplot = geom_point()
  • line chart = geom_line()
  • histogram = geom_histogram()
  • bar chart = geom_bar() or geom_col()
  • pie chart = geom_bar() with coord_polar()

ggplot(data_diamond_count, aes(cut, count)) +
  geom_col()

ggplot(diamonds, aes(x = factor(1), fill = factor(cut))) +
  geom_bar(width = 1) +
  coord_polar(theta = "y")

3.10.2 Exercise 2

• geom_path() connects points in order of appearance. geom_line connects points from left to right.

p + geom_path()

• geom_polygon() draws polygons which are filled paths.

p + geom_polygon() 

• geom_line() connects points from left to right.

p + geom_line() 

3.10.3 Exercise 3

• What low-level geoms are used to draw geom_smooth()?
  • geom_smooth() fits a smoother to data, displaying the smooth and its standard error, allowing you to see a dominant pattern within a scatterplot with a lot of “noise”. The low level geom for geom_smooth() are geom_path(), geom_area() and geom_point().

ggplot(mpg, aes(displ, hwy)) + 
  geom_point() + 
  geom_smooth()

## `geom_smooth()` using method = 'loess' and formula = 'y ~ x'

• What low-level geoms are used to draw geom_boxplot()?
  • Box plots are used to summarize the distribution of a set of points using summary statistics. The low level geom for geom_boxplot() are geom_rect(), geom_line() and geom_point().

ggplot(mpg, aes(drv, hwy)) + 
  geom_boxplot()

• What low-level geoms are used to draw geom_violin()?
  • Violin plots show a compact representation of the density of the distribution highlighting the areas where most of the points are found. The low level geom for geom_violin() are geom_area() and geom_path().

ggplot(mpg, aes(drv, hwy)) + 
  geom_violin()