Chapter 2 Getting started with RStudio

2.1 Use RStudio as a calculator

Copy the following commands into the bottom Console. After each command, press the Enter/Return key on your keyboard.

1+ exp(3) + sin(0.5)
x=c(1,2,3)
x^2
sum(x)
sum(x^3)

Alternatively, you can copy the commands into the top Script Window. Highlight all the commands, and pressRunfunction. Note that the output is in the bottom Console.

Many data sets are already loaded into R. They are good to experiment with, and are used in the R/LQuizzes.

data()

For example, we’re going to consider mtcars. To view the data, simple type its name.

mtcars

Clearly this is not recommended for large data sets! Instead, look at the first or last rows using the head or tail functions.

head(mtcars)
tail(mtcars, n=3)

help(mtcars)

It’s very important to set up a neat file management system for the semester. This is best practise, and will make your life easier!

RMarkdown is a clever document/file which can save all your Rcode and comments in one place for easy editing.

You have been given the file Lab1.Rmd on your Labs page on Canvas.
Download the file Lab1.Rmd, and store it in your new course folder DATA1001files.

Double-click on the file and notice how it automatically opens in the top LHS window of RStudio.

The information at the top is called the YAML, which you can edit it: eg in author: "xxx", replace your name for xxx.)
Render the file using Knit.

This will create Lab1.html, which you can open in a browser. This becomes your final report.

You can create new RMarkdown files by duplicating Lab1.Rmd and renaming it Project1.Rmd etc.
To customise your RMarkdown file, see RMarkdown Cheat Sheet

There is a handy way to streamline your workflow, so that the output of the .Rmd opens next to your input in the RStudio console. This makes it very easy to edit and see your results.

What to do if a package is missing?

Error in library(somepackage) : there is no package called âsomepackageâ

(Note, of course, somepackage is being used as a place holder here! Replace with the name of the actual package that is missing).

No need to fret! All we need to do is install the package somepackage from CRAN, which is a repository for R packages.
What is an R package? Good question. You can think of an R package like an app on the app store : it contains sets of functions that allow R to have extra functionality. For example, R was at the beginning, designed to be used very much like a calculator (very basic!). To be able to knit reports, we need new packages to enable R to extend its capabilities beyond the most basic packages downloaded with R.

install.packages("somepackage")

And R automatically searches and downloads for that package on CRAN. You can then try knitting your report again! Sometimes, more than one package will be missing - if this is the case - just repeat the steps above until they are all installed.

In summary:

If want to use a certain package, use the following code. This is a 1 off step. It will now appear in the list of packages in the bottom LHS window.

install.packages("somepackage")

Then every time, you start a new .Rmd document, or session in R, you need to call up the package by using library.

library("somepackage")