R Strings

🔤 R Strings – Complete Tutorial

In R, strings are used to store and manipulate text data such as names, messages, labels, file paths, and categorical values.
They are a core part of data analysis, reporting, and text processing.

1️⃣ What are Strings in R?

• Strings are character data

• Written inside quotes

  • Double quotes " "

  • Single quotes ' '

📌 Internally, R stores strings as character vectors.

2️⃣ Creating Strings

3️⃣ Printing Strings: print() vs cat() ⭐

📌 cat() interprets escape characters
📌 print() shows raw string

4️⃣ String Length – nchar() ⭐

5️⃣ Combine Strings – paste() & paste0() ⭐

paste()

paste0() (no space)

Custom Separator

6️⃣ Substring – substr() ⭐

7️⃣ Replace Text – gsub() ⭐

8️⃣ Find Text – grep() & grepl() ⭐

grepl() (TRUE/FALSE)

grep() (index)

9️⃣ Change Case ⭐

🔟 Trim Spaces – trimws() ⭐

1️⃣1️⃣ Split Strings – strsplit() ⭐

1️⃣2️⃣ Strings with NA Values ⚠️

📌 Handle NA carefully using is.na().

1️⃣3️⃣ Common String Functions (Quick Table)

1️⃣4️⃣ Common Mistakes ❌

❌ Forgetting quotes
❌ Confusing paste() & paste0()
❌ Indexing errors in substr()
❌ Ignoring NA values

📌 Interview Questions & MCQs

Q1. How are strings stored in R?

A) Integer
B) Logical
C) Character
D) Factor

✅ Answer: C

Q2. Which function joins strings without space?

A) paste()
B) paste0()
C) cat()
D) sprintf()

✅ Answer: B

Q3. Which function finds pattern and returns TRUE/FALSE?

A) grep()
B) grepl()
C) gsub()
D) substr()

✅ Answer: B

Q4. Which function removes leading/trailing spaces?

A) strip()
B) clean()
C) trimws()
D) remove()

✅ Answer: C

Q5. Output of:

A) 0
B) 1
C) 2
D) Error

✅ Answer: B

🔥 Real-Life Use Cases

✔ Text data cleaning
✔ File names & paths
✔ Report generation
✔ Data labeling
✔ NLP preprocessing

✅ Summary

• Strings are character data

• Created using quotes

• R provides powerful string functions

• paste(), substr(), grep() are essential

• Handle NA & spaces carefully

• Core topic for R exams, interviews & data science