List to vector conversion in R Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a list in R?

A list in R is a collection that can hold elements of different types and sizes, like numbers, strings, or even other lists.

beginner

What is a vector in R?

A vector in R is a sequence of elements of the same type, like all numbers or all characters, stored in a single structure.

beginner

How do you convert a list to a vector in R?

You can use the function unlist() to flatten a list into a vector by combining all elements into one sequence.

intermediate

What happens if the list contains elements of different types when using unlist()?

R will coerce all elements to a common type, usually converting everything to character if types differ, to create a single vector.

beginner

Write the R code to convert the list my_list <- list(1, 2, 3) to a vector.

Use my_vector <- unlist(my_list). This will create a numeric vector c(1, 2, 3).

Which R function converts a list to a vector?

A unlist()

B as.vector()

C list()

D c()

The function unlist() flattens a list into a vector.

What type of elements does a vector in R contain?

A Only lists

B Elements of the same type

C Only numbers

D Elements of different types

Vectors contain elements all of the same type, such as all numbers or all characters.

If a list contains numbers and characters, what will unlist() produce?

A A character vector

B A numeric vector

C A list

D An error

R coerces all elements to a common type, usually character, when types differ.

What does the following code return? unlist(list(1, 2, 3))

A A character vector

B A list with elements 1, 2, 3

C A numeric vector c(1, 2, 3)

D NULL

The list is flattened into a numeric vector with elements 1, 2, 3.

Which of these is NOT true about unlist()?

A It can convert nested lists to vectors

B It returns a vector

C It coerces elements to a common type

D It preserves the original list structure

unlist() does not preserve the list structure; it flattens it.

Explain how to convert a list to a vector in R and what happens if the list has mixed types.

Think about how R handles different data types when combining.

Describe the difference between a list and a vector in R with examples.

Consider how you store different items in a shopping bag vs. a row of identical boxes.