Logical indexing in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select elements greater than 3 from the vector.

R Programming

vec <- c(1, 4, 3, 5, 2)
result <- vec[vec [1] 3]
print(result)

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

A<

B!=

C==

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' selects elements less than 3, which is incorrect.

Using '==' selects elements equal to 3, not greater.

Using vec > 3 creates a logical vector selecting elements greater than 3.

2fill in blank

medium

Complete the code to select elements that are even numbers.

R Programming

vec <- c(2, 5, 8, 7, 10)
even_nums <- vec[vec %% 2 [1] 0]
print(even_nums)

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

A==

B<

C>

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' selects odd numbers, not even.

Using '>' or '<' does not correctly check for evenness.

Using vec %% 2 == 0 selects elements divisible by 2, i.e., even numbers.

3fill in blank

hard

Fix the error in the code to select elements not equal to 4.

R Programming

vec <- c(4, 6, 4, 8, 5)
result <- vec[vec [1] 4]
print(result)

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

A!=

B>=

C==

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' selects only elements equal to 4, not excluding them.

Using '>=' or '<=' does not exclude 4 properly.

Using vec != 4 selects elements that are not equal to 4.

4fill in blank

hard

Fill both blanks to select elements less than 5 and greater than 2.

R Programming

vec <- c(1, 3, 4, 6, 2)
result <- vec[vec [1] 5 & vec [2] 2]
print(result)

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

A<

B>

C<=

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<=' or '>=' changes the range to include boundary values.

Mixing up the operators reverses the logic.

Use < 5 and > 2 to select elements between 2 and 5.

5fill in blank

hard

Fill all three blanks to create a named vector with lengths of words longer than 3 characters.

R Programming

words <- c("cat", "house", "dog", "elephant")
lengths <- c([1] = [2] for [3] in words if nchar([3]) > 3)
print(lengths)

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

Aword

Bnchar(word)

Dlengths

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names causes errors.

Not using nchar() returns wrong values.

Use word as the name, nchar(word) as the value, and iterate over word in words.