Introduction

The data we will examine is loaded automatically with tidyverse. It is called mpg and contains fuel economy and characteristics of cars from the Environmental Protection Agency (EPA) from http://fueleconomy.gov.

To begin, familiarize yourself with the dataset by reading the documentation. Remember, you can pull up the documentation by running ?mpg in the console.

All plots should follow the best visualization practices we have discussed in lecture. Hence, plots should include an informative title, axes should be labeled, and careful consideration should be given to aesthetic choices.

In addition, code and narrative should not exceed the 80 character limit. To help police this, add a vertical line at 80 characters by clicking “Tools” \(\rightarrow\) “Global Options” \(\rightarrow\) “Code” \(\rightarrow\) “Display”, then set “Margin Column” to 80 and click “Apply”.

Your assignment should have at least three meaningful commits.

Exercises

1. Generate a scatterplot of city miles per gallon (cty) versus highway miles per gallon (hwy) with points colored by class.

2. Note that there are only so many possibilities of highway and city miles per gallon, so some of the points are on top of each other. Using geom_jitter() or a position = argument in geom_point(), add a small amount of random variation to each point. Briefly comment on the differences between the plots you constructed in Exercises 1 and 2. What are the advantages and disadvantages of each?

3. Examine the relationship between city and highway miles per gallon, with a separate plot for each type of drive train (drv).

4. Create side-by-side boxplots of city miles per gallon for each class. Briefly comment on what you notice.

5. Create a segmented bar chart with one bar per class, each bar going from 0 - 1, with the fill determined by the type of drive train (drv). What do you notice?

6. Recreate the plot below. The functions theme_bw() and labs() will be helpful. The size of the points is 0.50. Also, set the figure dimensions with appropriate code chunk options, where the width is 9 and the height is 6. Note: the figure dimensions below are distorted due to the formatting of this HTML file.