Apply family vs loops in R Programming - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to calculate the mean of each column using apply.

R Programming

result <- apply(data, [1], mean)

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

A2

B1

C3

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 instead of 2 applies the function to rows, not columns.

Using 0 or 3 causes an error or unexpected results.

The second argument in apply specifies the margin: 2 means apply the function to columns.

2fill in blank

medium

Complete the code to calculate the sum of each element in the list using lapply.

R Programming

result <- lapply(numbers, [1])

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Asum()

Blength

Cmean

Dsum

Attempts:

3 left

💡 Hint

Common Mistakes

Using sum() calls the function immediately instead of passing it.

Using mean or length applies the wrong function.

In lapply, you pass the function name without parentheses to apply it to each element.

3fill in blank

hard

Fix the error in the for loop to correctly calculate the squares of numbers.

R Programming

squares <- numeric(length(numbers))
for (i in [1](numbers)) {
  squares[i] <- numbers[i]^2
}

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

Alength

B1:length

Cseq_along

Drange

Attempts:

3 left

💡 Hint

Common Mistakes

Using length(numbers) alone does not create a sequence.

Using range(numbers) returns min and max, not a sequence.

seq_along(numbers) generates a sequence from 1 to the length of numbers, which is safe for indexing.

4fill in blank

hard

Fill both blanks to create a named vector with the mean of each column using sapply.

R Programming

result <- sapply(data, [1])
names(result) <- [2](data)

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Amean

Bcolnames

Crownames

Dsum

Attempts:

3 left

💡 Hint

Common Mistakes

Using sum instead of mean changes the calculation.

Using rownames assigns wrong names.

sapply applies mean to each column, and colnames gets the column names for naming the result.

5fill in blank

hard

Fill all three blanks to create a list of logical vectors indicating which elements are greater than 5 using lapply.

R Programming

result <- lapply(numbers, function(x) x [1] [2])
names(result) <- [3](numbers)

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

A>

B5

Cnames

Dlength

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of > changes the condition.

Using length instead of names assigns wrong names.

The anonymous function checks if each element is greater than 5 using > and 5. The names function assigns the original names to the result list.