Logical operators (&, |, !, &&, ||) in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to perform element-wise logical AND on vectors a and b.

R Programming

result <- a [1] b

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

A&&

B&

C|

D||

Attempts:

3 left

💡 Hint

Common Mistakes

Using '&&' instead of '&' causes only the first element to be compared.

Using '|' or '||' instead of AND operators.

In R, & performs element-wise logical AND between vectors.

2fill in blank

medium

Complete the code to perform element-wise logical OR on vectors x and y.

R Programming

result <- x [1] y

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

A!

B&&

C&

D|

Attempts:

3 left

💡 Hint

Common Mistakes

Using '&&' or '&' instead of OR operators.

Using '!' which is logical NOT.

The | operator performs element-wise logical OR in R.

3fill in blank

hard

Fix the error in the code to negate the logical vector v.

R Programming

negated <- [1]v

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

A!

B&

C&&

D|

Attempts:

3 left

💡 Hint

Common Mistakes

Using '&&' or '&' which are AND operators.

Using '|' which is OR operator.

The ! operator negates each element of a logical vector in R.

4fill in blank

hard

Fill both blanks to create a vector of TRUE where elements of a are TRUE and elements of b are FALSE.

R Programming

result <- a [1] [2]b

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

A&

B|

C!

D&&

Attempts:

3 left

💡 Hint

Common Mistakes

Using '|' instead of '&' for AND operation.

Not negating b before AND.

Use & for element-wise AND and ! to negate vector b.

5fill in blank

hard

Fill all three blanks to create a vector where elements are TRUE if a is TRUE or b is FALSE, but not both.

R Programming

result <- (a [1] ([2]b)) [3] (a [1] b)

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

A&

B|

C!

D^

Attempts:

3 left

💡 Hint

Common Mistakes

Using AND instead of OR.

Not using XOR to exclude both TRUE.

This expression uses OR |, NOT !, and XOR ^ to get TRUE where only one condition is TRUE.

Practice

1. Which logical operator in R checks every element of a vector and returns a vector of results?

easy

A. ==

B. & and |

C. !

D. && and ||

Solution

1. Step 1: Understand vectorized logical operators

   In R, & and | operate element-wise on vectors, returning a vector of TRUE/FALSE values for each element.

2. Step 2: Compare with single-element operators

   && and || only check the first element of the vectors and return a single TRUE/FALSE value.

3. Final Answer:

   & and | -> Option B

4. Quick Check:

   Element-wise operators = & and | [OK]

Hint: Use & and | for vectors, && and || for single values [OK]

Common Mistakes:

• Confusing && and & as the same
• Using || for vector comparisons
• Thinking ! works on multiple elements like &

2. Which of the following is the correct syntax to negate a logical vector v in R?

easy

A. !v

B. not(v)

C. ~v

D. v != TRUE

Solution

1. Step 1: Identify the negation operator in R

   The logical NOT operator in R is !, which negates each element of a logical vector.

2. Step 2: Check other options

   not() is not a base R function, ~ is a formula operator, and v != TRUE works but is less direct and less clear.

3. Final Answer:

   !v -> Option A

4. Quick Check:

   Negate vector with ! [OK]

Hint: Use ! to flip TRUE/FALSE values in R [OK]

Common Mistakes:

• Using not() which is not a base R function
• Confusing ~ with negation
• Using != TRUE instead of !

3. What is the output of the following R code?

v1 <- c(TRUE, FALSE, TRUE)
v2 <- c(FALSE, FALSE, TRUE)
v1 & v2
v1 && v2

medium

A. [1] TRUE TRUE TRUE
[1] TRUE

B. [1] TRUE FALSE TRUE
[1] TRUE

C. [1] FALSE FALSE FALSE
[1] FALSE

D. [1] FALSE FALSE TRUE
[1] FALSE

Solution

1. Step 1: Evaluate element-wise AND with &

   v1 & v2 compares each element:
   TRUE & FALSE = FALSE
   FALSE & FALSE = FALSE
   TRUE & TRUE = TRUE
   Result: [FALSE FALSE TRUE]

2. Step 2: Evaluate single-element AND with &&

   v1 && v2 checks only first elements:
   TRUE && FALSE = FALSE
   Result: [FALSE]

3. Final Answer:

   [1] FALSE FALSE TRUE [1] FALSE -> Option D

4. Quick Check:

   & compares all elements, && only first [OK]

Hint: & works element-wise; && checks first element only [OK]

Common Mistakes:

• Thinking && works element-wise
• Mixing up & and && results
• Ignoring vector length in &&

4. Identify the error in this R code snippet:

v <- c(TRUE, FALSE, TRUE)
if (v & TRUE) {
  print("Yes")
} else {
  print("No")
}

medium

A. Using & inside if condition causes error due to vector length

B. Missing parentheses around v & TRUE

C. Should use | instead of &

D. No error, code runs fine

Solution

1. Step 1: Understand if condition requirements

   The if statement expects a single TRUE or FALSE value, not a vector.

2. Step 2: Analyze v & TRUE

   v & TRUE returns a logical vector of length 3, which causes an error in if because it cannot handle multiple values.

3. Final Answer:

   Using & inside if condition causes error due to vector length -> Option A

4. Quick Check:

   if needs single TRUE/FALSE, & returns vector [OK]

Hint: Use && in if conditions for single TRUE/FALSE [OK]

Common Mistakes:

• Using & instead of && in if
• Assuming if accepts vector
• Ignoring error message about length

5. You have two logical vectors:

a <- c(TRUE, FALSE, TRUE, FALSE)
b <- c(FALSE, TRUE, TRUE, TRUE)

Write an expression using logical operators to find elements where either a is TRUE and b is FALSE, or a is FALSE and b is TRUE. What is the resulting vector?

hard

A. a | b resulting in [TRUE TRUE TRUE TRUE]

B. a & b resulting in [FALSE FALSE TRUE FALSE]

C. (a & !b) | (!a & b) resulting in [TRUE TRUE FALSE TRUE]

D. !(a | b) resulting in [FALSE FALSE FALSE FALSE]

Solution

1. Step 1: Understand the condition

   We want TRUE where exactly one of a or b is TRUE, but not both. This is the XOR condition.

2. Step 2: Write expression and evaluate

   (a & !b) | (!a & b) checks where a is TRUE and b is FALSE, or vice versa.
   Evaluate:
   a: TRUE FALSE TRUE FALSE
   b: FALSE TRUE TRUE TRUE
   a & !b: TRUE FALSE FALSE FALSE
   !a & b: FALSE TRUE FALSE TRUE
   OR: TRUE TRUE FALSE TRUE

3. Final Answer:

   (a & !b) | (!a & b) resulting in [TRUE TRUE FALSE TRUE] -> Option C

4. Quick Check:

   XOR = (a & !b) | (!a & b) [OK]

Hint: Use (a & !b) | (!a & b) for XOR logic [OK]

Common Mistakes:

• Using & or | alone instead of XOR logic
• Forgetting to negate one vector
• Confusing XOR with OR