Want to share your content on R-bloggers? click here if you have a blog, or here if you don't. In the exercises below we practice the basics of visualization in R. Firstly, we use the command: ` plot `. Then we will see how to add information to our plot through command: ` lines `. We will use the mtcars dataset, provided by R Cran (we can upload dataset by type ` mtcars ` and then attach our dataset by ` attach(mtcars)`). A description of the data is available here.

Answers to the exercises are available here.

If you obtained a different (correct) answer than those listed on the solutions page, please feel free to post your answer as a comment on that page.

Exercise 1
Plot Miles/(US) gallon versus Rear axle ratio by ` plot(mpg,drat) `. On which axis does mpg appear?
a. mpg appears on the x axis
b. mpg appears on the y axis

Exercise 2
Is a scatterplot recommended for continuous or dichotomous variables?
a. continuous
b. dichotomous

Exercise 3
Produce a histogram with ` hist(gear)`. What do you see?
a. frequencies
b. probability density

Exercise 4
Change type of visualization of our scatterplot in Exercise 1 ` plot(mpg,drat,type="")`. If we want to see lines what we have to type into “”:
a.type=”l”
b.type=”p”

Exercise 5
Now we want to see both point and lines in our plot. What we have to type into
` plot(mpg,drat,type="")`:
a.type=c(“p”,”l”)
b.type=”b”

Exercise 6
Add another variable to our plot, for example Weight. What command do we have to use:
a.`plot(mpg, drat); plot(mpg, wt)`
b.`plot(mpg, drat); points(mpg, wt)`

Exercise 7
Now we have added a new variable to our plot. Suppose we want to use two different colours to separate the points. Type ` plot(mpg, drat, col=2) `:
What colour have we selected:
a. red
b. green

Exercise 8
Now we want to differentiate the two different variables in the scatterplot:
a. Let’s change the colours of the second plot
b. Change use two different types of plot (e.g. points,lines)

Exercise 9
Now we want to highlight a variable in the final plot.
Type: `plot(mpg, drat, lwd=2) ; points(mpg, wt, lwd=1)`. Which plot is highlighted:
a. plot1 (mpg,drat)
b. plot2 (mpg,wt)

Exercise 10
Finally choose four different continuous variables from mtcars set and produce:
a.Plot with lines and points for different variables with different colours (hint: change
y axis parameters by adding command `ylim=c(0,30)` to plot [e.g. ` plot(a,b,type="p",ylim=c(0,30))`.
b.Choose one variable from each and highlighted it set red colour and a broad line