Foundations of
Data Science

Spring 2026 | Data 2 (399)
Jeffrey M. Girard | Lecture 02a

Roadmap

1. Install R and RStudio on your laptop computer

2. Learn to use the R Console as a scientific calculator

R and RStudio

Programming is a Superpower

• Programming is how we talk to and control our amazing computers

• It gives us power and flexibility

• Everything we do in this course will be accomplished via programming

• Programming will leave a record of what we did (i.e., code), so we can later reuse, adapt, and share it

Common Data Science Languages

General Purpose

• R (interactive, welcoming)
  • Strengths: statistics, data wrangling, data visualization
  • Weaknesses: relatively slow, not security-focused

• Python (popular, versatile)
  • Strengths: automation, machine learning, data wrangling
  • Weaknesses: relatively slow

• Java / C++ / Scala / Julia (faster but older and harder or newer and smaller)

Special Purpose

• JavaScript (web), SQL (databases), Swift (mobile), MATLAB (neuroscience), etc.

The R Ecosystem

1. Think of your computer as the engine of a car
   • It provides raw power for computation

2. The R language is like the controls for the car
   • It lets you apply and direct that power

3. RStudio is like a fancy dashboard for the car
   • It adds extra information and convenience

4. An R package is like an add-on for the car
   • It adds new features and capabilities

Installing R

Windows

1. Open a web browser
2. Visit cloud.r-project.org
3. Click “Download R for Windows”
4. Click the “base” subdirectory link
5. Click “Download R-4.X.X” (e.g., 4.5.2)
6. Run the downloaded .exe file
7. Select all the default options
8. Complete the installation wizard

Mac OS

1. Open a web browser
2. Visit cloud.r-project.org
3. Click “Download R for macOS”
4. Click “R-4.X.X.pkg” (e.g., 4.5.2)
5. Run the downloaded .pkg file
6. Select all the default options
7. Complete the installation wizard

Note. You will need to repeat this process every time a new version of R is released (every 4–5 months).

Installing RStudio

Windows

1. Open a web browser
2. Visit posit.co/download/rstudio-desktop
3. Scroll down until you find “2: Install RStudio”
4. Click “Download RStudio Desktop for Windows”
5. Run the downloaded .exe file
6. Select all the default options
7. Complete the installation wizard

Mac OS

1. Open a web browser
2. Visit posit.co/download/rstudio-desktop
3. Scroll down until you find “2: Install RStudio”
4. Click “Download RStudio Desktop for macOS 14/15/26”
5. Run the downloaded .dmg file
6. Select all the default options
7. Drag the RStudio icon to your Applications folder (if you want)

Note. You will need to repeat this process every time a new version of RStudio is released (every 2–4 months).

RStudio Window

Note. You can customize RStudio (e.g., the fonts, color themes, and pane layout) under “Tools > Global Options”.

Console

R will Grant your Wishes

• R is like a well-meaning but overly literal genie

  • It has the power to grant almost any wish
  • But we must phrase our wishes carefully!
  • We will always get what we ask for…
  • …but not always what we wanted.

• Mastering the R language means learning…

  • How to properly phrase commands
  • How to decipher error messages
  • How to view code from R’s perspective
  • How to detect and correct small mistakes

Communicating with R

• The Console is like a chat window with R
  • You send a command to R and get a response
  • Neither side of the conversation is saved

• An R Script is like an email thread with R
  • You send many commands to R all at once
  • Only your side of the conversation is saved

• A Quarto Document is like a scrapbook with R
  • You can combine code and formatted text
  • Both sides of the conversation are saved

Simple Operations

# Addition
10 + 3

[1] 13

# Subtraction
10 - 3

[1] 7

# Multiplication
10 * 3

[1] 30

# Division
10 / 3

[1] 3.333333

Errors to Avoid

# Only use * for multiplication
10 x 3

Error in parse(text = input): <text>:2:4: unexpected symbol
1: # Only use * for multiplication
2: 10 x
      ^

# Only use / for division
10 \ 3

Error in parse(text = input): <text>:2:4: unexpected '\\'
1: # Only use / for division
2: 10 \
      ^

Advanced Operations

# Exponentiation
10 ^ 2

[1] 100

# Default Order of Operations
10 + 3 * 2

[1] 16

# Override Order of Operations
(10 + 3) * 2

[1] 26

# Negative Numbers
10 + -30

[1] -20

Advanced Numbers

# Decimals
1.234

[1] 1.234

# Fractions
(1 / 3)

[1] 0.3333333

# Leading and Trailing Zeros
09.870

[1] 9.87

# Large Numbers
9876543

[1] 9876543

Errors to Avoid

# Don't include commas inside numbers
9,876,543

Error in parse(text = input): <text>:2:2: unexpected ','
1: # Don't include commas inside numbers
2: 9,
    ^

# Don't include spaces inside numbers
9 876 543

Error in parse(text = input): <text>:2:3: unexpected numeric constant
1: # Don't include spaces inside numbers
2: 9 876
     ^