R Markdown document creation in R Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple R Markdown chunk

What will be the output shown in the knitted document for this R Markdown chunk?

R Programming

```{r}
x <- 5
x * 2
```

A Error: object 'x' not found

B x * 2

C 5

D 10

💡 Hint

The chunk runs R code and shows the result of the last expression.

The variable x is assigned 5, then multiplied by 2. The output is the value 10.

🧠 Conceptual

intermediate

Purpose of YAML header in R Markdown

What is the main purpose of the YAML header at the top of an R Markdown document?

A To write R code that runs before the document

B To specify document metadata and output format

C To add comments inside the document

D To create tables and figures automatically

💡 Hint

YAML header is enclosed by --- lines and sets options for the whole document.

The YAML header defines metadata like title, author, date, and output format such as HTML or PDF.

🔧 Debug

advanced

Identify the error in this R Markdown chunk

What error will this R Markdown chunk produce when knitted?

R Programming

```{r}
summary(data.frame(a = 1:3, b = c('x', 'y')))
```

A Error: arguments imply differing number of rows: 3, 2

B No error, outputs summary of data frame

C Error: object 'data' not found

D Error: unexpected symbol in 'summary(data.frame(a = 1:3, b = c('

💡 Hint

Check if the vectors used to create the data frame have the same length.

The vector 'a' has length 3 but 'b' has length 2, so data.frame() fails with a row number mismatch error.

📝 Syntax

advanced

Correct syntax for including inline R code in R Markdown

Which option shows the correct way to include inline R code that prints the value of variable n in R Markdown text?

A {{n}}

B ${n}$

C `r n`

D <%= n %>

💡 Hint

Inline R code is enclosed in backticks with r before the expression.

Inline R code uses backticks and the letter r like `r expression` to evaluate and insert the result.

🚀 Application

expert

Number of output files generated by knitting an R Markdown document to HTML

If you knit an R Markdown document named report.Rmd to HTML, how many files are typically created in the output folder?

A One HTML file and one folder with supporting files

B One HTML file named report.html

C Only the original Rmd file is updated

D Multiple HTML files, one per code chunk

💡 Hint

Consider how images and dependencies are stored when knitting to HTML.

Knitting to HTML usually creates one HTML file plus a folder with images, CSS, and JavaScript needed for the document.

Practice

1. What is the main purpose of an R Markdown document?

easy

A. To store data in a spreadsheet format

B. To write only R code without any text

C. To create interactive web applications

D. To combine text and R code in one file for easy report generation

Solution

1. Step 1: Understand R Markdown's function

   R Markdown allows mixing text and R code in one document.

2. Step 2: Identify the purpose

   This combination is mainly used to create reports easily.

3. Final Answer:

   To combine text and R code in one file for easy report generation -> Option D

4. Quick Check:

   R Markdown = Text + R code for reports [OK]

Hint: Remember: R Markdown = text + code for reports [OK]

Common Mistakes:

• Thinking R Markdown is only for code
• Confusing with Shiny apps
• Assuming it's for data storage

2. Which of the following is the correct way to start an R code chunk in an R Markdown document?

easy

A. <r>```

B. ```r{

C. ```{r}

D. {r}```

Solution

1. Step 1: Recall R code chunk syntax

   R code chunks start with three backticks followed by {r} exactly.

2. Step 2: Match the correct syntax

   ```{r} matches the correct syntax: ```{r}

3. Final Answer:

   ```{r} -> Option C

4. Quick Check:

   Code chunk start = ```{r} [OK]

Hint: Code chunks start with three backticks and {r} [OK]

Common Mistakes:

• Placing {r} after backticks incorrectly
• Using angle brackets instead of backticks
• Missing curly braces

3. Given this R Markdown snippet, what will be the output in the final document?

```{r}
x <- 5
x * 2
```

medium

A. 10

B. x * 2

C. 5

D. Error: object 'x' not found

Solution

1. Step 1: Understand the code chunk execution

   The code assigns 5 to x, then calculates x * 2, which is 10.

2. Step 2: Determine output shown in document

   R Markdown shows the result of the last expression, which is 10.

3. Final Answer:

   10 -> Option A

4. Quick Check:

   5 * 2 = 10 [OK]

Hint: Last expression in chunk shows output [OK]

Common Mistakes:

• Expecting code to print the expression itself
• Confusing variable assignment with output
• Thinking error occurs due to chunk

4. You wrote this R Markdown chunk but get an error when knitting:

```{r}
print('Hello World'
```

What is the problem?

medium

A. Wrong chunk start syntax

B. Missing closing parenthesis in print function

C. Missing quotes around Hello World

D. Code chunk not closed with backticks

Solution

1. Step 1: Check the print statement syntax

   The print function is missing a closing parenthesis.

2. Step 2: Verify chunk syntax

   The chunk start and end are correct; quotes are present.

3. Final Answer:

   Missing closing parenthesis in print function -> Option B

4. Quick Check:

   print('text') needs closing ) [OK]

Hint: Count parentheses carefully in code chunks [OK]

Common Mistakes:

• Ignoring missing parenthesis errors
• Thinking chunk delimiters cause error
• Assuming quotes are missing

5. You want to create an R Markdown document with title "My Report", author "Alex", and output as HTML. Which YAML header is correct?

hard

A. ---
title: "My Report"
author: "Alex"
output: html_document
---

B. ---
title: My Report
author: Alex
output: pdf_document
---

C. ---
title: "My Report"
author: "Alex"
output: word_document
---

D. ---
title: My Report
author: Alex
output: html
---

Solution

1. Step 1: Identify correct YAML format for title, author, output

   YAML requires --- lines, key: value pairs, and output format as html_document for HTML output.

2. Step 2: Match options with correct YAML

   --- title: "My Report" author: "Alex" output: html_document --- uses quotes for strings and output: html_document, which is correct.

3. Final Answer:

   --- title: "My Report" author: "Alex" output: html_document --- -> Option A

4. Quick Check:

   YAML header with html_document output [OK]

Hint: Use output: html_document for HTML in YAML [OK]

Common Mistakes:

• Using pdf_document or word_document instead of html_document
• Missing quotes causing parsing errors
• Incorrect output format name