Logical (boolean) type in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a logical variable with value TRUE.

R Programming

flag <- [1]

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

Atrue

BTRUE

C"TRUE"

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase 'true' which is not recognized in R.

Using quotes around TRUE, which makes it a string, not logical.

In R, logical TRUE is written as TRUE (all uppercase, no quotes).

2fill in blank

medium

Complete the code to check if 5 is greater than 3 and store the result in a logical variable.

R Programming

result <- 5 [1] 3

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

A>

B<

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' which means less than.

Using '==' which checks equality, not greater than.

The expression 5 > 3 returns TRUE because 5 is greater than 3.

3fill in blank

hard

Fix the error in the code to correctly assign a logical FALSE value.

R Programming

is_valid <- [1]

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

A0

BFalse

C"FALSE"

DFALSE

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase 'False' which is not recognized in R.

Using quotes around FALSE, making it a string.

Logical FALSE in R is written as FALSE (all uppercase, no quotes).

4fill in blank

hard

Fill both blanks to create a logical vector with TRUE and FALSE values.

R Programming

vec <- c([1], [2])

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

ATRUE

BFALSE

C"TRUE"

D"FALSE"

Attempts:

3 left

💡 Hint

Common Mistakes

Using quoted strings instead of logical values.

Using lowercase true or false.

Logical vectors use TRUE and FALSE without quotes.

5fill in blank

hard

Fill all three blanks to create a logical vector with TRUE, FALSE, and the result of 2 == 2.

R Programming

vec <- c([1], [2], [3])

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

ATRUE

BFALSE

C2 == 2

D"TRUE"

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around TRUE or FALSE.

Using incorrect comparison operators.

The vector contains logical TRUE, logical FALSE, and the result of the comparison 2 == 2 which is TRUE.

Practice

1. What type of values does the logical type in R store?

easy

A. Numbers only

B. TRUE or FALSE

C. Text strings

D. Dates and times

Solution

1. Step 1: Understand logical type meaning

   Logical type in R is used to store values that represent truth values.

2. Step 2: Identify stored values

   These truth values are either TRUE or FALSE, not numbers, text, or dates.

3. Final Answer:

   TRUE or FALSE -> Option B

4. Quick Check:

   Logical type = TRUE or FALSE [OK]

Hint: Logical means true or false values only [OK]

Common Mistakes:

• Confusing logical with numeric type
• Thinking logical stores text
• Assuming logical stores dates

2. Which of the following is the correct way to create a logical vector in R?

easy

A. c('TRUE', 'FALSE')

B. c(1, 0, 1)

C. c(TRUE, FALSE, TRUE)

D. c(T, F, 'TRUE')

Solution

1. Step 1: Check vector creation syntax

   Logical vectors use TRUE or FALSE values without quotes inside c().

2. Step 2: Validate each option

   c(TRUE, FALSE, TRUE) uses proper logical values TRUE and FALSE. c('TRUE', 'FALSE') creates character vector. c(1, 0, 1) creates numeric vector. c(T, F, 'TRUE') mixes logical shortcuts T, F with string 'TRUE' coercing to character vector.

3. Final Answer:

   c(TRUE, FALSE, TRUE) -> Option C

4. Quick Check:

   Logical vector uses TRUE/FALSE without quotes [OK]

Hint: Use TRUE/FALSE without quotes for logical vectors [OK]

Common Mistakes:

• Using numbers instead of logical values
• Putting TRUE/FALSE in quotes
• Mixing logical and string types

3. What is the output of this R code?

result <- 5 > 3
print(result)

medium

A. TRUE

B. "TRUE"

C. FALSE

D. Error

Solution

1. Step 1: Evaluate the comparison 5 > 3

   Since 5 is greater than 3, the expression returns TRUE as a logical value.

2. Step 2: Understand print output

   print() outputs the logical value TRUE without quotes.

3. Final Answer:

   TRUE -> Option A

4. Quick Check:

   5 > 3 = TRUE [OK]

Hint: Comparison returns logical TRUE or FALSE, not strings [OK]

Common Mistakes:

• Thinking output is string "TRUE"
• Confusing TRUE with FALSE
• Expecting an error from comparison

4. Identify the error in this R code snippet:

flag <- TRUE
if flag == TRUE {
  print("Yes")
}

medium

A. Variable flag is not defined

B. Incorrect logical value TRUE

C. print() function is wrong

D. Missing parentheses around condition in if statement

Solution

1. Step 1: Check if statement syntax in R

   In R, the condition in if() must be inside parentheses.

2. Step 2: Identify missing parentheses

   The code uses if flag == TRUE without parentheses, causing syntax error.

3. Final Answer:

   Missing parentheses around condition in if statement -> Option D

4. Quick Check:

   if() needs parentheses [OK]

Hint: Always put condition inside parentheses in if() [OK]

Common Mistakes:

• Omitting parentheses in if condition
• Misusing TRUE value
• Assuming print() syntax is wrong

5. Given a numeric vector nums <- c(0, 1, 2, 3, 0), which R expression correctly creates a logical vector indicating which elements are non-zero?

hard

A. nums != 0

B. nums == TRUE

C. is.logical(nums)

D. nums > TRUE

Solution

1. Step 1: Understand the goal

   We want a logical vector showing TRUE where elements are not zero.

2. Step 2: Evaluate each option

   nums != 0 returns TRUE for non-zero elements. nums == TRUE compares to 1 (TRUE coerces to 1), TRUE only where nums==1. is.logical(nums) checks type of nums, returns single FALSE since it's numeric. nums > TRUE compares to 1, TRUE only where nums > 1.

3. Final Answer:

   nums != 0 -> Option A

4. Quick Check:

   nums != 0 gives logical TRUE for non-zero [OK]

Hint: Use != 0 to find non-zero elements logically [OK]

Common Mistakes:

• Using == TRUE to compare numbers
• Using is.logical() to check or create logical vector
• Comparing numbers directly to TRUE