Variable scope (lexical scoping) in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign the value 10 to variable x.

R Programming

x <- [1]

Drag options to blanks, or click blank then click option'

ATRUE

B"x"

C10

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Putting quotes around 10, which makes it a string instead of a number.

Using TRUE or NULL instead of a number.

The variable x is assigned the numeric value 10 using the assignment operator <-.

2fill in blank

medium

Complete the function to return the value of y defined outside the function.

R Programming

y <- 5
my_func <- function() {
  return([1])
}

Drag options to blanks, or click blank then click option'

Ay

Bx

Cz

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a variable not defined outside the function.

Returning a literal number instead of the variable.

The function returns the variable y which is defined outside the function, demonstrating lexical scoping.

3fill in blank

hard

Fix the error by completing the code to access the outer variable a inside the function.

R Programming

a <- 3
outer_func <- function() {
  inner_func <- function() {
    return([1])
  }
  inner_func()
}

Drag options to blanks, or click blank then click option'

Aa

Binner_func

C3

Db

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable not defined in any scope.

Returning the function name instead of a variable.

The inner function accesses the variable a from the outer scope, showing lexical scoping.

4fill in blank

hard

Complete the function to compute compound interest using the outer 'rate' variable.

R Programming

rate <- 1.05
compound_interest <- function(principal) {
  return([1])
}

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Aprincipal * 1.05

Bprincipal * rate

Cprincipal + rate

Drate * principal + 1

Attempts:

3 left

💡 Hint

Common Mistakes

Hardcoding the rate value like 1.05.

Adding instead of multiplying.

The function uses rate from the outer scope via lexical scoping to compute the interest correctly without hardcoding the value.

5fill in blank

hard

Complete the function to use the outer 'exponent' despite the local shadowing variable.

R Programming

exponent <- 3
power_calc <- function(base) {
  exponent_local <- 2
  return([1])
}

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Aexponent ^ base

Bbase ^ exponent_local

Cbase ** 3

Dbase ^ exponent

Attempts:

3 left

💡 Hint

Common Mistakes

Using the local shadowed variable exponent_local.

Hardcoding the exponent value.

Lexical scoping allows access to the outer exponent (3), ignoring the local exponent_local (2), so 2^3 = 8.