Lecture 4: Commands and Calculations in R

Overview

• In this lecture, we’ll explore:
  • How to type commands into the R console.
  • Performing basic calculations in R.
  • Storing numeric values in variables.
  • Using R as a calculator for arithmetic operations.

1. Typing Commands in the R Console

• What is the R Console?
  • The Console Panel in RStudio is where you can directly type and execute R commands.
  • You can use the console to quickly run commands and view their output.
• Example: Printing a message:
  • In the console, try typing the following command to print a message:

print("Hello, World!")

[1] "Hello, World!"

2. Doing Basic Calculations in R

• Using R as a calculator:
  • R can perform basic arithmetic operations just like a calculator.
  • You can add, subtract, multiply, divide, and use exponents directly in the console.
• Example: Simple arithmetic:

3 + 5  # Addition

[1] 8

10 - 4  # Subtraction

[1] 6

6 * 7  # Multiplication

[1] 42

8 / 2  # Division

[1] 4

2^3  # Exponentiation (2 raised to the power of 3)

[1] 8

• Note: Comments in R can be written using #. Any text following # will be ignored by R when executing commands.

3. Storing Numbers as Variables

• What is a variable in R?
  • A variable in R is a way to store a value or result that you can reuse later in your code.
• Example: Assigning a value to a variable:

x <- 10  # Assign the value 10 to the variable x
y <- 5   # Assign the value 5 to the variable y

• How to use variables:
  • Once a variable is assigned, you can use it in calculations or other commands.
• Example: Using variables in calculations:

result <- x + y  # Add x and y, store the result in a new variable 'result'
result

[1] 15

• Important notes:
  • In R, the assignment operator is <-, which assigns a value to a variable.
  • You can view the contents of any variable by typing its name in the console and hitting Enter.

4. Using Built-in Functions

• What are functions in R?
  • Functions are predefined operations or procedures that take input, perform specific tasks, and return a result.
  • R includes a vast number of built-in functions for various tasks such as calculations, data manipulation, and statistical analysis.
• Example: Calculating the square root:

sqrt(25)

[1] 5

• Example: Finding the sum of a vector:

numbers <- c(1, 2, 3, 4, 5)  # Create a vector of numbers
sum(numbers)

[1] 15

• Additional basic functions:
  • mean() – Calculates the average of a set of numbers.
  • length() – Returns the number of elements in a vector or list.
  • min() and max() – Returns the smallest or largest value from a vector.

Key Takeaways

• You have learned how to use the R console to run basic commands and calculations.
• R can perform a variety of arithmetic operations, and you can store results in variables for reuse.
• Built-in functions, such as sqrt() and sum(), are powerful tools for performing calculations in R.

Looking Forward

• In the next lecture, we’ll dive deeper into functions, exploring how to create your own custom functions and use them to solve more complex problems in R.