Comparison operators in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if x is equal to 10.

R Programming

x <- 10
result <- x [1] 10
print(result)

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

A=

B!=

C<-

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using = instead of == for comparison.

Using <- which is for assignment, not comparison.

In R, == is used to compare if two values are equal.

2fill in blank

medium

Complete the code to check if y is greater than 5.

R Programming

y <- 7
if (y [1] 5) {
  print("y is greater than 5")
}

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

A>

B<

C==

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of >.

Using == which checks equality, not greater than.

The operator > checks if the left value is greater than the right value.

3fill in blank

hard

Fix the error in the code to check if z is not equal to 0.

R Programming

z <- 3
if (z [1] 0) {
  print("z is not zero")
}

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

A<

B==

C!=

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using = which is for assignment, not comparison.

Using == which checks equality, not inequality.

The operator != means 'not equal to' in R.

4fill in blank

hard

Complete the code to create a dictionary of words and their lengths, but only for words longer than 3 letters.

R Programming

words <- c("cat", "house", "dog", "elephant")
lengths <- list()
for (word in words) {
  if (nchar(word) [1] 3) {
    lengths[[word]] <- nchar(word)
  }
}

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

A>

B<

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of > in the condition.

Adding an operator when assigning the length.

The condition nchar(word) > 3 selects words longer than 3 letters. The {{BLANK_2}} is empty because we just assign the length.

5fill in blank

hard

Fill both blanks to create a named list of uppercase words and their lengths, only if length is at least 4.

R Programming

words <- c("tree", "sun", "flower", "sky")
result <- list()
for (w in words) {
  if (nchar(w) [1] 3) {
    result[[[2]]] <- nchar(w)
  }
}

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

A>

Btoupper(w)

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of > in the condition.

Not converting the word to uppercase for the name.

Adding an operator when assigning the length.

The condition nchar(w) > 3 filters words with length at least 4. The name uses toupper(w) to uppercase the word. No operator is needed when assigning the length.

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