Running R code in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print "Hello, world!" in R.

R Programming

print([1])

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

AHello, world!

B"Hello, world!"

Cprint("Hello, world!")

Decho "Hello, world!"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around the text

Using print without quotes

Using echo instead of print

In R, to print text, you use print() with the text in quotes.

2fill in blank

medium

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

R Programming

[1] <- 10

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

Avalue

B10

Cassign

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Putting 10 on the left side

Using = instead of <-

Using assign() function incorrectly

In R, the assignment operator <- assigns values to variables.

3fill in blank

hard

Fix the error in the code to calculate the sum of numbers 1 to 5.

R Programming

total <- [1](1:5)

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

Asum

Brange

Cadd

Dtotal

Attempts:

3 left

💡 Hint

Common Mistakes

Using add() instead of sum()

Using range() which returns min and max

Using variable names instead of functions

The sum() function calculates the total of a numeric vector in R.

4fill in blank

hard

Fill both blanks to create a vector of numbers from 1 to 10 and get its length.

R Programming

numbers <- [1](1, 10)
length_of_numbers <- [2](numbers)

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

Aseq

Blength

Csum

Dc

Attempts:

3 left

💡 Hint

Common Mistakes

Using c() instead of seq() for sequence

Using sum() instead of length()

Mixing up function names

seq(1, 10) creates a sequence from 1 to 10; length() returns the number of elements.

5fill in blank

hard

Fill all three blanks to create a named vector with scores and get the names of the vector.

R Programming

scores <- c([1] = 90, [2] = 85, [3] = 88)
names(scores)

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

AMath

BScience

CEnglish

DHistory

Attempts:

3 left

💡 Hint

Common Mistakes

Using numbers instead of names

Using incorrect subject names

Forgetting to name the vector elements

Named vectors use names like Math, Science, English to label scores.

Practice

1. What does running R code mean?

easy

A. Installing R software

B. Only writing comments in the script

C. Saving files without executing them

D. Typing commands or running script files to perform tasks

Solution

1. Step 1: Understand the meaning of running code

   Running code means executing commands or scripts to perform actions in R.

2. Step 2: Identify the correct description

   Typing commands or running script files matches the definition of running R code.

3. Final Answer:

   Typing commands or running script files to perform tasks -> Option D

4. Quick Check:

   Running code = executing commands/scripts [OK]

Hint: Running code means executing commands or scripts [OK]

Common Mistakes:

• Confusing running code with just writing comments
• Thinking saving files runs code
• Mixing running code with installing software

2. Which of the following is the correct way to run an R script named script.R from the console?

easy

A. source('script.R')

B. run('script.R')

C. execute('script.R')

D. load('script.R')

Solution

1. Step 1: Recall the function to run scripts in R

   The function source() is used to run R scripts from the console.

2. Step 2: Match the correct syntax

   source('script.R') correctly runs the script named script.R.

3. Final Answer:

   source('script.R') -> Option A

4. Quick Check:

   Run script = source() [OK]

Hint: Use source() to run R scripts from console [OK]

Common Mistakes:

• Using run() which is not an R function
• Using execute() which does not exist in R
• Using load() which loads data, not scripts

3. What will be the output of the following R code?

print(2 + 3 * 4)

medium

A. 14

B. 20

C. 24

D. Error

Solution

1. Step 1: Understand operator precedence in R

   Multiplication (*) has higher precedence than addition (+), so 3 * 4 is calculated first.

2. Step 2: Calculate the expression

   3 * 4 = 12, then 2 + 12 = 14.

3. Final Answer:

   14 -> Option A

4. Quick Check:

   2 + (3 * 4) = 14 [OK]

Hint: Multiply before adding in R expressions [OK]

Common Mistakes:

• Adding before multiplying ignoring precedence
• Expecting error due to syntax
• Confusing multiplication with addition

4. Identify the error in the following R code snippet:

print('Hello World)

medium

A. Missing closing parenthesis for print

B. Missing closing quote for the string

C. print() is not a valid function in R

D. No error, code runs fine

Solution

1. Step 1: Check string syntax

   The string starts with a single quote but does not have a matching closing quote.

2. Step 2: Confirm the error type

   This causes a syntax error because the string is not properly closed.

3. Final Answer:

   Missing closing quote for the string -> Option B

4. Quick Check:

   Unclosed string = syntax error [OK]

Hint: Always close quotes around strings [OK]

Common Mistakes:

• Thinking print() is invalid in R
• Ignoring missing quote and blaming parentheses
• Assuming code runs without errors

5. You want to run multiple R commands stored in a file named analysis.R. Which is the best way to run all commands at once and see their output in the console?

hard

A. Open the file and run each line manually

B. Copy and paste the file content into the console line by line

C. Use source('analysis.R') to run the whole script

D. Restart R and open the file without running it

Solution

1. Step 1: Understand how to run multiple commands in R

   Running a whole script at once is done using the source() function.

2. Step 2: Identify the best method for running all commands and seeing output

   source('analysis.R') runs all commands in the file and shows output in the console.

3. Final Answer:

   Use source('analysis.R') to run the whole script -> Option C

4. Quick Check:

   Run script = source() [OK]

Hint: Use source() to run entire R scripts at once [OK]

Common Mistakes:

• Running lines manually wastes time
• Copy-pasting line by line is inefficient
• Restarting R does not run code automatically