Running R code in R Programming - Mini Project: Build & Apply

Running R code

📖 Scenario: You want to learn how to run simple R code to do basic calculations and see the results.

🎯 Goal: Write and run R code step-by-step to create variables, perform calculations, and print the results.

📋 What You'll Learn

Create variables with exact names and values

Use arithmetic operations in R

Print output using print()

💡 Why This Matters

🌍 Real World

Running R code is the first step to analyzing data, creating reports, and building statistical models.

💼 Career

Many jobs in data science, statistics, and research require running R code to process and understand data.

1

Create variables

Create a variable called a and set it to 10. Create another variable called b and set it to 5.

R Programming

# Create variables a and b with values 10 and 5
# Your code here

Hint

Use the assignment operator <- to assign values to variables in R.

2

Calculate sum

Create a variable called sum_ab that stores the sum of a and b.

R Programming

a <- 10
b <- 5
# Calculate sum_ab as a + b
# Your code here

Hint

Use the + operator to add two variables.

3

Calculate product

Create a variable called product_ab that stores the product of a and b.

R Programming

a <- 10
b <- 5
sum_ab <- a + b
# Calculate product_ab as a * b
# Your code here

Hint

Use the * operator to multiply two variables.

4

Print results

Use print() to display the values of sum_ab and product_ab.

R Programming

a <- 10
b <- 5
sum_ab <- a + b
product_ab <- a * b
# Print sum_ab and product_ab
# Your code here

Hint

Use print(variable_name) to show the value of a variable.

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