Instructions

In Chapter 12, we explored many different ways to “look at” the numbers. For this lab, let’s explore the mtcars dataset that is included within R.

This activity description does not provide the same level of code prompts as previous labs – it is assumed that you remember or can look up the necessary code. The overall goal of this activity is to use ggplot2 to show different attributes of the mtcars dataset. Please be sure to include both the code and the images that were generated with your assignment.

Add all of your libraries that you use for this assignment here.

# Add your library below.
library(ggplot2)
# library(ggplot2)

Generate the following visualizations:

Step 1 - Histogram

Histogram of mpg

# Write your code below.
# Generate a histogram of 'mpg' (Miles per Gallon) from the mtcars dataset

ggplot(mtcars, aes(x = mpg)) + 
  geom_histogram(binwidth = 2, fill = "blue", color = "black") + 
  labs(title = "Histogram of Miles Per Gallon (mpg)", x = "mpg", y = "Count")

Step 2 - Boxplots

Boxplots of mpg by cyl (i.e. 3 box plots: one for all cars with 4 cylinders, one for all cars with 6 cylinders, and one with all the cars with 8 cylinders).

# Write your code below.
# Generate boxplots of `mpg` by `cyl`
ggplot(mtcars, aes(x = factor(cyl), y = mpg)) + 
  geom_boxplot(fill = "lightblue") + 
  labs(title = "Boxplot of mpg by Cylinder", x = "Number of Cylinders", y = "mpg")

Step 3 - MultiLine chart

MultiLine chart of wt on the x-axis, mpg for the y-axis. With a line for each am (i.e. two lines). Also be sure to show each point on the chart.

# MultiLine chart of 'wt' on the x-axis and 'mpg' on the y-axis, with separate lines for each transmission type ('am')
ggplot(mtcars, aes(x = wt, y = mpg, color = factor(am))) + 
  geom_line() + 
  geom_point() + 
  labs(title = "MultiLine Chart of wt vs mpg by Transmission", 
       x = "Weight (wt)", 
       y = "Miles per Gallon (mpg)",
       color = "Transmission (am)") + 
  scale_color_discrete(labels = c("Automatic", "Manual"))

Step 4 - Barchart

Barchart with the x-axis being the name of each car, and the height being wt. Make sure to rotate the x-axis labels, so we can actually read the car name.

# Write your code below.
# Generate a barchart with car names on the x-axis and car weight ('wt') on the y-axis
# To make the chart more readable, we rotate the x-axis labels so that car names are visible vertically
ggplot(mtcars, aes(x = rownames(mtcars), y = wt)) + 
  geom_bar(stat = "identity", fill = "lightgreen") + 
  labs(title = "Car Weight by Model", x = "Car Model", y = "Weight (wt)") + 
  theme(axis.text.x = element_text(angle = 90, hjust = 1))

Step 5 - Scatter chart

Scatter chart with the x-axis being the mpg and the y-axis being the wt of the car. Have the color and the size of each “symbol” (i.e., circle) represent how fast the car goes (based on the qsec attribute).

# Generate a scatter chart with 'mpg' on the x-axis and 'wt' on the y-axis
# The color and size of each point represent 'qsec' (Quarter Mile Time), showing how fast each car is
ggplot(mtcars, aes(x = mpg, y = wt, color = qsec, size = qsec)) + 
  geom_point() + 
  labs(title = "Scatter Chart of wt vs mpg with qsec", 
       x = "Miles per Gallon (mpg)", 
       y = "Weight (wt)", 
       color = "Quarter Mile Time (qsec)", 
       size = "Quarter Mile Time (qsec)")