Assignment operators in R Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of compound assignment with addition

What is the output of the following R code?

R Programming

x <- 5
x += 3
print(x)

A Error: unexpected '=' in "x +="

B [1] 5

C [1] 3

D [1] 8

💡 Hint

R does not support the '+=' operator like some other languages.

In R, the '+=' operator is not valid syntax. Using it causes an error because R expects '<-' or '=' for assignment.

❓ Predict Output

intermediate

Correct way to add and assign in R

Which option correctly adds 3 to variable x and assigns the result back to x in R?

R Programming

x <- 5
# Add 3 to x and assign back

A x =+ 3

B x += 3

C x <- x + 3

D x <-+ 3

💡 Hint

Use the standard assignment operator with an expression.

In R, you add and assign by writing 'x <- x + 3'. The '+=' operator is not supported.

❓ Predict Output

advanced

Output of chained assignment

What is the output of this R code?

R Programming

a <- b <- 10
print(a)
print(b)

A Error: invalid syntax

B

[1] 10
Error: object 'b' not found

C

[1] 20
[1] 10

D

[1] 10
[1] 10

💡 Hint

In R, assignment can be chained from right to left.

The expression assigns 10 to b, then assigns b to a, so both become 10.

❓ Predict Output

advanced

Output of assignment with global environment

What is the output of this R code?

R Programming

x <- 5
f <- function() {
  x <<- 10
  print(x)
}
f()
print(x)

A

[1] 10
[1] 5

B

[1] 10
[1] 10

C

[1] 5
[1] 5

D Error: object 'x' not found

💡 Hint

The '<<-' operator assigns to the variable in the parent environment.

Inside the function, 'x <<- 10' changes the global x to 10, so both prints show 10.

🧠 Conceptual

expert

Behavior of assignment operators in R environments

Which statement best describes the difference between '<-' and '<<-' assignment operators in R?

A '<-' assigns a value in the current environment; '<<-' assigns a value in the parent environment or higher if not found.

B '<-' assigns a value in the current environment; '<<-' assigns a value in the global environment only.

C '<-' assigns a value globally; '<<-' assigns a value locally within a function.

D '<-' and '<<-' are interchangeable and have no difference in scope.

💡 Hint

Think about how R searches environments when assigning with '<<-'.

The '<-' operator assigns in the current environment. The '<<-' operator looks up the parent environments and assigns to the first found variable or creates it in the global environment if none found.