Comparison operators in R Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the == operator do in R?

The == operator checks if two values are equal and returns TRUE if they are, otherwise FALSE.

beginner

How do you check if one value is greater than another in R?

Use the > operator to check if the left value is greater than the right value. It returns TRUE or FALSE.

beginner

What is the difference between == and != in R?

== checks if two values are equal, while != checks if two values are NOT equal.

beginner

What do the operators <= and >= mean in R?

<= means 'less than or equal to' and >= means 'greater than or equal to'. They compare two values and return TRUE or FALSE.

intermediate

How does R handle comparison of vectors with comparison operators?

R compares vectors element by element and returns a logical vector of TRUE or FALSE for each comparison.

What will 5 == 5 return in R?

A TRUE

B FALSE

C 5

D Error

== checks equality and returns TRUE if values are equal.

Which operator checks if two values are NOT equal in R?

A <=

B ==

C >=

D !=

!= means 'not equal to' and returns TRUE if values differ.

What does 3 >= 4 return?

A FALSE

B TRUE

C 3

D 4

3 >= 4 means '3 greater than or equal to 4', which is false.

How does R compare vectors with < operator?

A Throws an error

B Compares only first elements

C Element-wise comparison returning logical vector

D Returns a single TRUE or FALSE

R compares each element of vectors and returns a logical vector.

What is the result of c(1,2,3) == 2 in R?

A TRUE TRUE TRUE

B FALSE TRUE FALSE

C TRUE FALSE TRUE

D FALSE FALSE FALSE

Only the second element equals 2, so result is FALSE TRUE FALSE.

Explain how comparison operators work in R and give examples of at least three different operators.

Think about how you check if two things are equal or one is bigger than the other.

Describe how R handles comparison when using vectors instead of single values.

Imagine comparing two lists of numbers one by one.

Practice

1. Which of the following comparison operators in R checks if two values are equal?

easy

A. !=

B. =

C. <>

D. ==

Solution

1. Step 1: Understand equality operator in R

   In R, the operator to check if two values are equal is ==.

2. Step 2: Differentiate from other operators

   = is for assignment, != means not equal, and <> is not valid in R.

3. Final Answer:

   == -> Option D

4. Quick Check:

   Equality operator = == [OK]

Hint: Use double equals (==) to test equality in R [OK]

Common Mistakes:

• Using single = instead of ==
• Confusing != with equality
• Using <> which is invalid in R

2. Which of the following is the correct syntax to check if variable x is NOT equal to 10 in R?

easy

A. x != 10

B. x <> 10

C. x =! 10

D. x !== 10

Solution

1. Step 1: Identify the not equal operator in R

   R uses != to check if two values are not equal.

2. Step 2: Check syntax correctness

   <> and !== are not valid in R, and =! is incorrect syntax.

3. Final Answer:

   x != 10 -> Option A

4. Quick Check:

   Not equal operator = != [OK]

Hint: Use != to check inequality in R [OK]

Common Mistakes:

• Using <> which is invalid in R
• Writing =! instead of !=
• Using !== which is from other languages

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

x <- 5
y <- 7
x > y

medium

A. FALSE

B. TRUE

C. 5

D. Error

Solution

1. Step 1: Compare values of x and y

   x is 5 and y is 7, so 5 > 7 is being checked.

2. Step 2: Evaluate the comparison

   Since 5 is not greater than 7, the expression returns FALSE.

3. Final Answer:

   FALSE -> Option A

4. Quick Check:

   5 > 7 = FALSE [OK]

Hint: Compare numbers directly; 5 > 7 is false [OK]

Common Mistakes:

• Confusing > with <
• Expecting numeric output instead of logical
• Thinking it causes an error

4. Identify the error in this R code snippet:

if (x = 10) { print("Yes") }

medium

A. No error, code is correct

B. Missing curly braces

C. Using = instead of ==

D. print() is incorrect function

Solution

1. Step 1: Check the condition syntax in if statement

   In R, to compare values, use ==, not =.

2. Step 2: Understand the difference between assignment and comparison

   = assigns a value, but == tests equality. Using = in if condition causes an error or unexpected behavior.

3. Final Answer:

   Using = instead of == -> Option C

4. Quick Check:

   Comparison needs ==, not = [OK]

Hint: Use == for comparison inside if() [OK]

Common Mistakes:

• Using = instead of ==
• Ignoring syntax errors from wrong operator
• Thinking = works for comparison

5. You want to filter a vector v <- c(3, 5, 7, 9) to keep only values greater than or equal to 5. Which R expression correctly uses comparison operators to do this?

hard

A. v[v => 5]

B. v[v >= 5]

C. v[v = 5]

D. v[v >== 5]

Solution

1. Step 1: Understand filtering with comparison

   To keep values >= 5, use the operator >= inside the indexing brackets.

2. Step 2: Check syntax correctness

   =>, =, and >== are invalid operators in R.

3. Final Answer:

   v[v >= 5] -> Option B

4. Quick Check:

   Use >= for greater or equal in filtering [OK]

Hint: Use >= for greater or equal comparisons [OK]

Common Mistakes:

• Using => which is invalid
• Using = instead of comparison operator
• Combining > and == incorrectly