Named vectors in R Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a named vector in R?

A named vector in R is a vector where each element has a name attached to it. These names help identify elements by name instead of just by position.

beginner

How do you assign names to a vector in R?

You can assign names to a vector using the names() function. For example: names(x) <- c('a', 'b', 'c') assigns names 'a', 'b', and 'c' to the elements of vector x.

beginner

How can you access elements of a named vector by name?

You can access elements by using the name inside square brackets. For example, if x is a named vector, x['name'] returns the element with the name 'name'.

intermediate

What happens if you assign duplicate names to elements in a named vector?

If you assign duplicate names, R allows it but accessing by name returns all elements with that name. This can cause confusion, so unique names are recommended.

beginner

How do you remove names from a named vector?

You can remove names by setting them to NULL using names(x) <- NULL. This makes the vector unnamed again.

Which function is used to assign names to a vector in R?

A names()

B colnames()

C rownames()

D dimnames()

The names() function is used to assign or get names of vector elements.

How do you access the element named 'age' in a named vector v?

A v[age]

B v$age

C v['age']

D v.age

You access named vector elements using square brackets and the name as a string: v['age'].

What will names(c(10, 20, 30)) return if no names are assigned?

A c('', '', '')

B c('10', '20', '30')

C An error

D NULL

If no names are assigned, names() returns NULL.

If a named vector has duplicate names, what happens when you access by that name?

A Returns only the first element with that name

B Returns all elements with that name

C Returns NULL

D Throws an error

Accessing by a duplicate name returns all elements with that name.

How do you remove all names from a named vector x?

A Both C and D

B names(x) <- ''

C x <- unname(x)

D names(x) <- NULL

You can remove names by setting names(x) <- NULL or by using unname(x).

Explain what a named vector is and how it can be useful in R programming.

Think about how names act like labels on elements.

Describe how to assign, access, and remove names from a vector in R.

Focus on the names() function and indexing.