Lesson 4: Stat Transformations: Bar plots, box plots, and histograms

The following questions will have you explore the mtcars dataset through creating plots that were presented in Lesson 4. At the end of these exercises, you should be more comfortable creating plots that convey statistical summary information about data.

Activate packages

library(ggplot2)

Load the mtcars dataset using the code below. This is a dataset that comes with R.

data(mtcars)

Question 1

How many cars in this dataset have 4, 6, or 8 cylinders (cyl)?

ggplot(mtcars,aes(x=factor(cyl)))+geom_bar(fill="ivory4")

Question 2

Does the number of cylinders (cyl) that a car has influence it's quarter mile time (qsec)?

ggplot(mtcars,aes(x=factor(cyl),y=qsec))+stat_summary(fun=mean,position=position_dodge(width=0.95),geom="bar",fill = "ivory4")+stat_summary(fun.data=mean_sdl,fun.args=list(mult=1),tion=position_dodge(width=0.95),geom="errorbar",width=0.5)

## Warning: Ignoring unknown parameters: tion

Question 3

What is the distribution of fuel efficiency (mpg)? Use 7 bins for this exercise.

ggplot(mtcars,aes(x=mpg))+geom_histogram(fill="orange",bins=7)

Question 4

Can you create a box plot of horsepower (hp) as a function of the number of cylinders (cyl) a car has?

ggplot(mtcars,aes(x=factor(cyl),y=hp))+geom_boxplot(colour="orangered")