Introduction to R

R is a programming language built for statistics and data analysis — it lets you load data, compute summaries, run statistical models, and draw publication-quality charts with very little code.

Learn Introduction to R in our free R course — a beginner-friendly interactive lesson with worked examples, a practice exercise and a quick reference.

Part of the free R course at LearnCodingFast — hands-on lessons with examples you run in your browser, plus practice exercises and a quick quiz.

By the end of this lesson you'll understand what R is and why analysts love it, how to use R as a calculator, how to store values in variables, and you'll have run your own first lines of R code.

What You'll Learn in This Lesson

1️⃣ Your First Lines of R

In R you don't need a main() function or any boilerplate. You type an expression and R evaluates it. To keep a value around for later, you assign it to a name with the <- operator (read it as "gets"). Read the worked example below — every line is explained — then run it yourself.

Notice the [1] in front of each result. That's not an error — it's R telling you the output starts at the first element. Because R treats even a single number as a one-element vector , every printed result carries an index. You'll see why that matters in the Vectors lesson.

2️⃣ R as a Calculator with Memory

R shines as an interactive calculator. You can do arithmetic directly, store intermediate results in variables, and call built-in functions using the name(arguments) pattern. The c() function ("combine") builds a vector — the structure R is built around.

In one line — mean(scores) — R averaged four numbers at once. That "do it to the whole collection" style is the heart of R and is what makes data analysis so concise.

3️⃣ Types and Getting Help

Every value in R has a type, which you can inspect with class() . When you're unsure how a function works, R's built-in help is excellent — type ?mean to open the documentation for mean .

Your turn. The script below works once you fill in the two # TODO blanks. Follow the hints, then run it and compare with the expected output.

Mini-Challenge: An "About Me" Report

No blanks this time — just a brief and an outline. Write it yourself, run it, and check your output against the example in the comments. Tiny programs like this build real fluency fast.

Common Errors (and the fix)

• "could not find function 'Mean'" — R is case-sensitive. The function is mean() , not Mean() . Check capitalisation of every function and variable name.
• "object 'x' not found" — You used a variable before assigning it, or mistyped its name. Assign it first with x <- 5 , then use it.
• Using < - with a space — x < - 5 means "is x less than -5?", not assignment. Write the arrow with no space: x <- 5 .
• Unbalanced quotes or parentheses — If the console shows a + prompt, R is waiting for you to finish an expression. Press Esc and check for a missing " or ) .

Pro Tips

• 💡 Use <- for assignment: while = works, the community convention is <- . In RStudio, press Alt + - to type it instantly.
• 💡 Try snippets instantly: use a free online runner like rdrr.io/snippets to test code without installing anything.
• 💡 Read the [1] : it's an index, not an error. Long results wrap onto several lines, each starting with the index of its first value.

📋 Quick Reference — R Basics

Task

R Syntax

Assign a value

x <- 5

Print a value

print(x)

Combine into a vector

c(1, 2, 3)

Average a vector

mean(x)

Check a type

class(x)

Open help

?mean

Frequently Asked Questions

🎉 Lesson Complete!

• ✅ R is a language built for statistics and data analysis
• ✅ You assign values with the <- operator
• ✅ R is vectorized — the [1] in output is an index
• ✅ Call functions with name(arguments) , e.g. mean(scores)
• ✅ Check types with class() and get help with ?
• ✅ Next lesson: RStudio & Running Code — set up a comfortable place to work

Practice quiz

Continue this course

• Next: RStudio & Running Code