Blog Home

R for Data Science 10.2.1 Exercises

Nov 5, 2023

From R for Data Science Exercises 8.2.4

1-Create a scatterplot of hwy vs. displ where the points are pink filled in triangles.

ggplot(mpg, aes(x=displ, y= hwy)) +
  geom_point(color="pink")

2-Why did the following code not result in a plot with blue points?

ggplot(mpg) + 
  geom_point(aes(x = displ, y = hwy, color = "blue"))

The color argument is within aes, but should be outside of it like

ggplot(mpg, aes(x = displ, y = hwy)) + 
  geom_point(  color = "blue")

3-What does the stroke aesthetic do? What shapes does it work with? (Hint: use ?geom_point)

ggplot(mpg, aes(x = displ, y = hwy)) + 
  geom_point(shape = 21, stroke = 2)

It provides the width of border of the point, and works with shapes that have borders.

4-What happens if you map an aesthetic to something other than a variable name, like aes(color = displ < 5)? Note, you’ll also need to specify x and y.

ggplot(mpg, aes(x = displ, y = hwy)) + 
  geom_point(aes(colour = displ < 5))    

It provides the color based on if the point is > < 5 then.