Logical (boolean) type in R Programming - Mini Project: Build & Apply

Working with Logical (Boolean) Type in R

📖 Scenario: You are analyzing survey data where participants answered yes or no questions. The answers are stored as logical values: TRUE for yes and FALSE for no.

🎯 Goal: You will create a logical vector representing answers, set a threshold for counting positive answers, count how many answers are TRUE, and then print the count.

📋 What You'll Learn

Create a logical vector called answers with the exact values TRUE, FALSE, TRUE, TRUE, FALSE

Create a variable called threshold and set it to 2

Use a variable called true_count to count how many TRUE values are in answers

Print the value of true_count

💡 Why This Matters

🌍 Real World

Logical (boolean) values are used in surveys, decision making, and filtering data based on yes/no or true/false answers.

💼 Career

Understanding logical types helps in data analysis, programming conditions, and controlling program flow in many jobs like data science and software development.

1

Create the logical vector

Create a logical vector called answers with these exact values: TRUE, FALSE, TRUE, TRUE, FALSE

R Programming

# Create the logical vector answers with TRUE, FALSE, TRUE, TRUE, FALSE
# Your code here

Hint

Use the c() function to create a vector of logical values.

2

Set the threshold value

Create a variable called threshold and set it to 2

R Programming

answers <- c(TRUE, FALSE, TRUE, TRUE, FALSE)
# Create the variable threshold and set it to 2
# Your code here

Hint

Just assign the number 2 to the variable threshold.

3

Count the TRUE values

Create a variable called true_count that counts how many TRUE values are in the answers vector

R Programming

answers <- c(TRUE, FALSE, TRUE, TRUE, FALSE)
threshold <- 2
# Count how many TRUE values are in answers and store in true_count
# Your code here

Hint

Use the sum() function because TRUE counts as 1 and FALSE as 0.

4

Print the count of TRUE values

Print the value of true_count

R Programming

answers <- c(TRUE, FALSE, TRUE, TRUE, FALSE)
threshold <- 2
true_count <- sum(answers)
# Print true_count
# Your code here

Hint

Use the print() function to show the count.

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