Introduction to R

Session 1

Gabriel Andrade

Introduction to R

Session 1

Today we will start using R and RStudio.

We will also create the project folder that we will use throughout the course.

What is R?

R is a language and environment designed for statistical and graphical operations.

R allows us to work with data by writing code.

That may sound intimidating at first, but the goal is not to become a programmer overnight.

A very short history of R

R was developed in the early 1990s by Ross Ihaka and Robert Gentleman.

It was inspired by an earlier language called S.

The problem with S? You had to buy it. And we all know we would rather spend our money on more important things…

Like food 🍔

R logo

Why is R useful?

R is:

  • Free
  • Open source
  • Widely used in science and data analysis
  • Supported by a large community
  • Extremely flexible

You do not need to learn everything R can do.

You only need to start building the tools that are useful for your own work.

What is RStudio?

R does the work.

RStudio helps us work with R.

RStudio makes it easier to:

  • write code
  • save scripts
  • organize files
  • view plots
  • install packages
  • manage projects

Having fun with R: Artwork by Allison Horst

The RStudio interface

RStudio User Guide 2026.08.2

Console vs. Script

Console

Good for quick tests.

2 + 2
10 / 2

But Console commands are not automatically saved.

Script

Better for real work.

# My first R script

2 + 2
5 * 4
100 / 10

Scripts allow us to save, edit, and reuse our code.

First code

Open a new R script:

File → New File → R Script

Then write:

2 + 2
5 * 4
100 / 10

Run each line from the script:

Windows: Ctrl + Enter

Mac: Command + Enter

Comments

We can add notes to scripts using #.

# My first R script

2 + 2

# Multiplication
5 * 4

# Division
100 / 10

Anything after # is ignored by R.

Comments help your future self understand what your code was doing.

RStudio Projects

An RStudio Project connects RStudio with a specific folder on your computer.

That folder can contain everything related to your work:

my-project/
│
├── data/
├── scripts/
├── outputs/
└── my-project.Rproj

Create our course project

Today we will create one project that we will use throughout the course.

Name it:

intro-r-course

Then create three folders:

intro-r-course/
│
├── data/
├── scripts/
└── outputs/

Why use projects?

Projects help us avoid this:

final.csv
final2.csv
final_revised.csv
final_revised2.csv
script.R
script_new.R
figure1.png

scattered across:

Desktop/
Downloads/
Documents/

A project gives your work a home.

Why learn R?

You may be wondering:

Why do I need to learn R after spending years getting good at Excel?

A selfish reason:

In many courses, labs, graduate programs, and research projects, knowing some R is already expected.

Good reasons to learn R

  • Reproducibility
    You can save and share exactly what you did.

Not just so that someone can replicate it exactly and know whether it’s right or wrong, but also so that others can learn from it.

  • It’s like learning a language
    It exercises your brain and helps you improve your quantitative reasoning. That’s not just my opinion—science says so [@auker2020].

  • A new skill in your arsenal
    Programming skills are increasingly in demand and highly valued [@lai2019]. Not only in academia but also in industry, knowing how to handle, visualize, and analyze data can be a huge advantage [@feng2020]. I’m not saying everyone has to be an expert, but everyone should at least have a basic understanding.

  • (Almost) endless possibilities
    These days, R isn’t just for statistics, you can do so many things with it. From documents and infographics to memes (yes, there’s even a package for making memes). Personally, I’ve learned the most about R when I combine it with my hobbies, creating graphs, exploring time-series data, music, and even politics, among other things.

https://cran.r-project.org/web/packages/meme/vignettes/meme.html

What can you do with R?

Data

Clean, organize, and explore datasets.

Statistics

Fit simple and complex models.

Graphics

Create figures, maps, and animations.

Documents

Create reports, websites, presentations, and manuscripts.

Apps

Build interactive tools to explore data.

Automation

Avoid doing repetitive tasks by hand.

The R community

Allison Horst code hero

R has a large and generous community.

There are tutorials, books, forums, examples, packages, and people willing to help.

You will not learn R today

R is learned by practicing.

You will:

  • make mistakes,
  • get errors,
  • forget commands,
  • reuse old scripts,
  • search for help,
  • and slowly become more comfortable.

Errors are part of learning R

You are going to see errors.

A lot of them.

That is normal.

R is not about avoiding errors.

It is about making enough of them that you eventually learn how to fix them.

Learning R takes time

In conclusion, whether or not you learn R will depend on how much time you spend on it, not on whether or not you take this tutorial. [@lawlor2022]

Allison Horst rollercoaster

Practice at home

Before the next session:

  1. Open your intro-r-course project.
  2. Create a new R script.
  3. Save it in scripts/ as:
practice-01.R
  1. Write and run at least 20 simple calculations.
  2. Add comments using # explaining each line of code you wrote, the title of the script, and your name.
  3. Close RStudio and reopen the project using the .Rproj file.

Keep writing code

The easiest way to learn R is to use it.

You do not need to memorize every command.

Write code, make mistakes, modify examples, and keep your old scripts.