Welcome

Why This Book Exists

You will make errors in R. Lots of them.

That’s not a prediction—it’s a promise. And it’s exactly how learning works.

Most R books teach you how to do things right. This book teaches you what happens when things go wrong, because:

  1. You learn more from errors than successes - Each error is a teaching moment
  2. Errors reveal R’s internal logic - Understanding why something fails helps you understand how R thinks
  3. You’ll spend more time debugging than writing new code - Better to learn it systematically
  4. Error messages are often cryptic - But they follow patterns once you know what to look for

How This Book Works

The Error-First Approach

Each chapter follows this structure:

  1. Show the error/warning - You’ll see it in a red/yellow box
  2. Explain what causes it - The underlying R behavior
  3. Demonstrate the solution - Multiple approaches when applicable
  4. Provide practice problems - Intentionally broken code for you to fix

Organization System

We use visual indicators throughout:

  • 🔴 ERROR: Stops execution completely
  • 🟡 WARNING: Continues but alerts you to potential issues
  • 🔵 MESSAGE: Informational only
  • ✅ SOLUTION: The fix

Difficulty Levels:

  • ⭐ Beginner - Everyone encounters these
  • ⭐⭐ Intermediate - Common with experience
  • ⭐⭐⭐ Advanced - Edge cases and complex scenarios

Error Categories:

  • 🔤 Syntax/Typo
  • 📦 Package Issue
  • 🔢 Type Mismatch
  • 📏 Dimension/Length
  • 💾 File/Path
  • 🧮 Mathematical
  • 🔗 Scoping/Environment

Who This Book Is For

  • Complete beginners who want to understand R deeply from the start
  • Self-taught R users who’ve been “googling errors” and want systematic knowledge
  • Python/MATLAB/SAS users transitioning to R and confused by its quirks
  • Data scientists who use R daily but want to master debugging
  • Teachers looking for a new pedagogical approach

What You’ll Need

  • R (version 4.0 or higher recommended)
  • RStudio (latest version)
  • Patience and curiosity
  • Willingness to intentionally break things

Book Structure

This book is organized into 16 parts:

Part I: Foundation & Environment - Installation, paths, basic objects

Part II: Data Types & Coercion - Understanding R’s type system through errors

Part III: Indexing & Subsetting - The most common source of errors

Part IV: Data Frames & Matrices - Rectangular data structures

Part V: Factors - R’s most misunderstood data type

Part VI: Strings & Characters - Text manipulation errors

Part VII: Functions & Programming - Control flow and function errors

Part VIII: Data Manipulation - base R, tidyverse, and data.table

Part IX: Graphics - Base graphics and ggplot2 errors

Part X: Statistical Operations - Math and modeling errors

Part XI: File I/O - Reading and writing data

Part XII: Packages & Namespaces - Installation and loading issues

Part XIII: Memory & Performance - Resource limitations

Part XIV: Date/Time - Temporal data challenges

Part XV: Advanced Topics - OOP, parallel processing, Shiny, etc.

Part XVI: Debugging & Best Practices - Tools and strategies

Conventions Used

Code Blocks

Code that produces an error:

# This will error
x <- c(1, 2, 3)
x[5]  # Subscript out of bounds? No! It returns NA

Expected output or error:

#> [1] NA

Icons and Symbols

  • 💡 Key insight
  • ⚠️ Common pitfall
  • 🎯 Best practice
  • 🔍 Deep dive
  • 📝 Exercise
  • 🚀 Performance tip

Companion Materials

All code is available at: github.com/guokai8/r-errors-book

  • Practice datasets
  • Additional exercises
  • Error reference cards
  • Community forum for questions

How to Read This Book

For Beginners

Read sequentially. Part I and II are foundational. Don’t skip ahead—the errors build on each other.

For Intermediate Users

Use the error index (Appendix A) to find specific errors, but read the related chapters for context.

For Advanced Users

Focus on Parts VIII-XV for package-specific and advanced errors. The appendices are your quick reference.

For Teachers

Each chapter has exercises at the end. The “Try It Yourself” sections contain intentionally broken code for students to fix.

Acknowledgments

This book wouldn’t exist without the thousands of confused R users who’ve posted their errors on Stack Overflow, the R-help mailing list, and various forums. Every error message in this book has frustrated someone—probably multiple people. This is for all of us.

Feedback

Find an error in the book about errors? See an error we haven’t covered? Open an issue on GitHub or email guokai8@gmail.com.

Now, let’s start breaking things…