Inline R code in R Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of inline R code in a string

What is the output of this R code when run?

R Programming

name <- "Alice"
result <- paste0("Hello, `r name`!")
print(result)

A "Hello, `r name`!"

B "Hello, Alice!"

C Error: object 'name' not found

D "Hello, NULL!"

💡 Hint

Inline R code inside strings with backticks is not evaluated automatically in base R.

In base R, backticks with `r` inside strings are not evaluated. The string remains as is.

❓ Predict Output

intermediate

Evaluating inline R code with glue package

What is the output of this R code?

R Programming

library(glue)
name <- "Bob"
result <- glue("Hello, {name}!")
print(result)

A "Hello, {name}!"

B Error: object 'name' not found

C "Hello, Bob!"

D "Hello, NULL!"

💡 Hint

The glue package evaluates expressions inside curly braces {}.

The glue function evaluates {name} and replaces it with the value of the variable name.

❓ Predict Output

advanced

Output of inline R code in R Markdown chunk

In an R Markdown document, what will this inline R code produce when rendered? `r 2 + 3 * 4`

A Error: object not found

B 14

C 20

D 2 + 3 * 4

💡 Hint

Inline R code in R Markdown evaluates the expression and inserts the result.

The expression 2 + 3 * 4 evaluates as 2 + 12 = 14.

❓ Predict Output

advanced

Error from incorrect inline R code syntax

What error does this R code produce? `r if(TRUE) print("Yes") else print("No")`

A NULL

B "Yes"

C "No"

D Error: unexpected 'else' in "else"

💡 Hint

Inline R code expects a single expression, not a full if-else statement.

The inline code syntax does not allow multi-line or compound statements like if-else without braces.

🧠 Conceptual

expert

How inline R code is processed in R Markdown

Which statement best describes how inline R code (e.g., `r expression`) is processed in an R Markdown document?

A The expression inside `r` is evaluated during knitting and its result replaces the inline code in the output.

B The inline code is treated as plain text and appears unchanged in the output document.

C The expression is evaluated only when the document is opened in RStudio, not during knitting.

D The inline code is executed in a separate R session after the document is rendered.

💡 Hint

Think about when the R Markdown document is converted to output formats.

During knitting, R Markdown evaluates inline R code and inserts the results into the output document.