Switch statement in R Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a switch statement in R?

A switch statement in R lets you choose one action from many based on a value. It helps run different code depending on the input.

beginner

How do you write a basic switch statement in R?

Use switch(value, case1 = result1, case2 = result2, ...). R checks the value and runs the matching case.

intermediate

What happens if no case matches in a switch statement?

If no case matches, switch returns NULL or the default if provided as the last unnamed argument.

intermediate

Can switch in R use numeric values as cases?

Yes, switch can use numeric values. When the first argument is numeric, it picks the case by position number.

beginner

Example: What does switch('b', a = 1, b = 2, c = 3) return?

It returns 2 because the value 'b' matches the case named 'b'.

In R, what does switch(2, 'apple', 'banana', 'cherry') return?

A 'banana'

B 'apple'

C 'cherry'

D NULL

When the first argument is numeric, switch returns the case at that position. Position 2 is 'banana'.

What does switch('x', a = 1, b = 2) return if 'x' is not a case?

A NULL

B 2

C 1

D Error

If no case matches and no default is given, switch returns NULL.

Which of these is the correct way to add a default case in switch?

A switch(x, a=1, b=2, default=3)

B switch(x, a=1, b=2, 3)

C switch(x, a=1, b=2, else=3)

D switch(x, a=1, b=2, default())

The last unnamed argument acts as the default if no named case matches.

If you want to select the third case by position, what should the first argument be?

A NULL

B '3'

C 'c'

D 3

When the first argument is numeric, switch picks the case by position number.

What type of values can the first argument of switch be?

A Only numeric

B Only character strings

C Either numeric or character

D Only logical

The first argument can be numeric (to pick by position) or character (to pick by name).

Explain how the switch statement works in R and how it differs when the first argument is numeric versus character.

Think about how you pick an option from a list by number or by name.

Describe how to provide a default case in an R switch statement and what happens if no case matches and no default is given.

What happens if you ask for a flavor not on the menu?