lapply and sapply in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to apply the function to each element of the list using lapply.

R Programming

result <- lapply(my_list, [1])

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

Alist

Bsum

Cc

Dmean

Attempts:

3 left

💡 Hint

Common Mistakes

Using a function that does not accept a vector input.

Using a function that returns a list instead of a numeric value.

The lapply function applies the given function to each element of the list and returns a list of results. Here, sum is the function applied.

2fill in blank

medium

Complete the code to apply the function to each element of the list and simplify the result using sapply.

R Programming

result <- sapply(my_list, [1])

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

Alength

Blist

Csum

Dc

Attempts:

3 left

💡 Hint

Common Mistakes

Using a function that returns a list, which prevents simplification.

Using a function that returns the length, which is correct but not the intended answer here.

The sapply function applies the function to each element and tries to simplify the result. Using sum will return a numeric vector of sums.

3fill in blank

hard

Fix the error in the code to correctly apply the mean function to each element using lapply.

R Programming

result <- lapply(my_list, [1])

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

Amean

Bsum

Clength

Dmedian

Attempts:

3 left

💡 Hint

Common Mistakes

Including parentheses after the function name inside lapply.

Using a function that does not calculate the mean.

The lapply function expects a function name without parentheses. Using mean without parentheses correctly passes the function.

4fill in blank

hard

Fill both blanks to create a named vector of the lengths of each element in the list using sapply.

R Programming

lengths <- sapply([1], [2])

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

Amy_list

Blength

Csum

Dmean

Attempts:

3 left

💡 Hint

Common Mistakes

Using sum instead of length for counting elements.

Using a variable name that does not exist.

The sapply function applies length to each element of my_list, returning a named vector of lengths.

5fill in blank

hard

Fill both blanks to create a list of squared values for each element in the list using lapply.

R Programming

squares <- lapply(my_list, function(x) x[1][2])

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

A*

B2

C^

D**

Attempts:

3 left

💡 Hint

Common Mistakes

Using the multiplication operator '*' instead of the power operator '^'.

Using the wrong exponent.

The anonymous function squares each element by using the power operator ^ with exponent 2: function(x) x^2. lapply applies it to each element and returns a list.