R Function Quiz

What does the following R function do?

• 5

• Error

• 15

• Nothing

What does the ... (ellipsis) represent in an R function?

• A placeholder for arguments that will be passed explicitly

• The function will return an error

• The function can accept a variable number of arguments

• A default argument

Which of the following functions is used to apply a function to each element of a list and returns a list?

• apply()

• sapply()

• lapply()

• mapply()

What will the following code return?

• 15

• 13

• 5

• 10

What is the purpose of sapply() in R?

• Apply a function to each element of a list and return a vector or matrix

• Apply a function to each element of a list and return a list

• Apply a function to rows/columns of a matrix

• Apply a function to multiple arguments

Which of the following is a key feature of lapply in R?

• Returns a data frame.

• Applies a function to elements of a list and returns a list.

• Applies a function to a data frame column-wise.

• Applies a function to each element of a vector and returns a matrix.

Which function would you use to apply a function to rows or columns of a matrix?

• mapply

• lapply

• apply

• sapply

Which of the following represents the correct use of apply to calculate the mean of rows in a matrix mat?

• apply(mat, 1, mean)

• apply(mat, 2, mean)

• apply(mat, mean)

• apply(mean, mat, 1)

What does the following code do?

• Returns the square of each element in the list.

• Returns the modulus (remainder) of each element in the list divided by 2.

• Returns TRUE if each element is even, otherwise FALSE.

• Returns the result of dividing each element by 2.

What is the key difference between apply() and lapply()?

• apply() is only used for numeric matrices, while lapply() works on lists.

• apply() works on matrices, while lapply() works on lists .

• apply() always simplifies the output, while lapply() cannot simplify results.

• There is no difference; they perform the same operations.