Vector indexing (1-based) in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to access the first element of the vector.

R Programming

vec <- c(10, 20, 30)
first_element <- vec[[1]]

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

A0

B1

C-1

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 as an index, which returns an empty vector.

Using negative indices incorrectly to exclude elements.

In R, vector indexing starts at 1, so the first element is accessed with index 1.

2fill in blank

medium

Complete the code to access the third element of the vector.

R Programming

numbers <- c(5, 15, 25, 35)
third <- numbers[[1]]

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

A2

B0

C4

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or 4 to access the third element.

Confusing zero-based indexing from other languages.

The third element is accessed with index 3 because R uses 1-based indexing.

3fill in blank

hard

Fix the error in the code to correctly access the second element.

R Programming

values <- c(100, 200, 300)
second_value <- values[[1]]

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

A2

B3

C-2

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or negative numbers as indices.

Using index 3 which accesses the third element instead.

Index 2 accesses the second element in R vectors.

4fill in blank

hard

Fill both blanks to create a vector of squares for elements greater than 2.

R Programming

vec <- c(1, 2, 3, 4, 5)
squares <- vec[vec [1] 2]^[2] 2

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

A>

B<

C**

D^

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of > for filtering.

Using ** which is not the exponent operator in R.

We select elements greater than 2 using > and square them using the ^ operator.

5fill in blank

hard

Complete the code to access the last element of the vector.

R Programming

vec <- c(10, 20, 30, 40, 50)
last_element <- vec[[1]]

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

A-1

B5

Clength(vec)

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using -1, which excludes the first element in R.

Hardcoding the value 5.

Using 0 as an index.

In R, the last element can be accessed using length(vec) as the index since indexing is 1-based.