(Yet More) Exercises

1. Run the following lines of code. Which of the two plots is saved as mpg-plot.png? Why?

ggplot(mpg, aes(x = class)) +
  geom_bar()
ggplot(mpg, aes(x = cty, y = hwy)) +
  geom_point()
ggsave("mpg-plot.png")

It will run the second. In looking at ?ggplot2::ggsave, we see that it defaults to the most recent plot run.

2. What do you need to change in the code above to save the plot as a PDF instead of a PNG? How could you find out what types of image files would work in ggsave()?

Changing filename in ggsave() to end in .pdf instead of .png will change the type. Looking at the function documentation, we see there are options for: “eps”, “ps”, “tex” (pictex), “pdf”, “jpeg”, “tiff”, “png”, “bmp”, “svg” and “wmf” (windows only).