Assignment operators in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign the value 10 to the variable x.

R Programming

x [1] 10

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

A=

B->

C<-

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' which is a comparison operator, not assignment.

Using '->' which assigns in the opposite direction.

In R, the most common assignment operator is <-, which assigns the value on the right to the variable on the left.

2fill in blank

medium

Complete the code to assign the value 5 to the variable y using the rightward assignment operator.

R Programming

5 [1] y

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

A<-

B->

C=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<-' which assigns leftward.

Using '==' which is for comparison.

The rightward assignment operator -> assigns the value on the left to the variable on the right.

3fill in blank

hard

Fix the error in the code to correctly assign 20 to variable z.

R Programming

z [1] 20

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

A<-

B==

C->

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of an assignment operator.

Using '=' which is valid but less common in R for assignment.

The operator <- correctly assigns the value 20 to variable z. The operator == is for comparison, not assignment.

4fill in blank

hard

Fill both blanks to assign the value 15 to variable a using the standard assignment operator and then print a.

R Programming

a [1] 15
print([2])

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

A<-

Ba

Cprint

D->

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'print' as the assignment operator.

Printing the wrong variable.

Use <- to assign 15 to a. Then print the value of a by passing it to the print() function.

5fill in blank

hard

Fill all three blanks to assign 30 to variable b, then assign b's value to c, and finally print c.

R Programming

b [1] 30
c [2] b
print([3])

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

A<-

B->

Cc

Db

Attempts:

3 left

💡 Hint

Common Mistakes

Using the rightward assignment operator incorrectly.

Printing the wrong variable.

Use <- to assign 30 to b, then assign b to c. Finally, print c to see the value.

Practice

1. Which of the following is the preferred assignment operator in R to store a value in a variable?

easy

A. <-

B. =

C. ==

D. ->

Solution

1. Step 1: Understand assignment operators in R

   R uses several operators to assign values, but the most common and preferred is <-.

2. Step 2: Differentiate from other operators

   = can assign but is less preferred; == is for comparison; -> assigns in reverse direction.

3. Final Answer:

   <- -> Option A

4. Quick Check:

   Preferred assignment operator = <- [OK]

Hint: Remember: <- points to the variable name [OK]

Common Mistakes:

• Confusing == (comparison) with assignment
• Using = instead of preferred <-
• Thinking -> is the usual assignment

2. Which of the following lines correctly assigns the value 10 to variable x in R?

easy

A. x == 10

B. x <- 10

C. 10 -> x <-

D. x =< 10

Solution

1. Step 1: Check each syntax for assignment

   x == 10 is a comparison, not assignment; 10 -> x <- is invalid syntax; x =< 10 is invalid.

2. Step 2: Confirm correct assignment syntax

   x <- 10 correctly assigns 10 to x using preferred operator.

3. Final Answer:

   x <- 10 -> Option B

4. Quick Check:

   Correct assignment uses <- [OK]

Hint: Use <- to assign values, not == or invalid symbols [OK]

Common Mistakes:

• Using == instead of <- for assignment
• Writing invalid operators like =<
• Mixing assignment directions incorrectly

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

x <- 5
y <- 3
x <- x + y
print(x)

medium

A. 5

B. Error

C. 3

D. 8

Solution

1. Step 1: Trace initial assignments

   Variable x is 5, y is 3.

2. Step 2: Update x with x + y

   x <- x + y means x becomes 5 + 3 = 8.

3. Final Answer:

   8 -> Option D

4. Quick Check:

   x after addition = 8 [OK]

Hint: x <- x + y adds y to x and updates x [OK]

Common Mistakes:

• Thinking x remains 5 after addition
• Confusing assignment with comparison
• Expecting print to show y instead of x

4. Identify the error in this R code snippet:

a <- 4
b <- 2
a =+ b
print(a)

medium

A. Runtime error because b is undefined

B. No error; output is 6

C. Syntax error due to =+ operator

D. Output is 4 because a is unchanged

Solution

1. Step 1: Analyze the operator used

   =+ is not a valid assignment or arithmetic operator in R.

2. Step 2: Understand correct syntax

   To add b to a and assign, use a <- a + b or a += b (not valid in base R).

3. Final Answer:

   Syntax error due to =+ operator -> Option C

4. Quick Check:

   Invalid operator =+ causes syntax error [OK]

Hint: Use <- for assignment; =+ is invalid in R [OK]

Common Mistakes:

• Using =+ instead of <- or +=
• Assuming += works like other languages
• Ignoring syntax errors in assignment

5. Given the code below, what will be the value of z after execution?

x <- 2
y <- 3
z <- x
z <- z * y
z <- z + x

hard

A. 8

B. Error

C. 7

D. 10

Solution

1. Step 1: Assign initial values

   x is 2, y is 3, z is assigned value of x, so 2.

2. Step 2: Multiply z by y

   z <- z * y means z = 2 * 3 = 6.

3. Step 3: Add x to z

   z <- z + x means z = 6 + 2 = 8.

4. Final Answer:

   8 -> Option A

5. Quick Check:

   z = (x * y) + x = 8 [OK]

Hint: Update z stepwise: multiply then add x [OK]

Common Mistakes:

• Adding before multiplying
• Confusing variable values
• Expecting z to remain initial x