Introduction
In this chapter, you will learn about variables in R, how to create them, and the rules for naming them. Understanding how to use variables effectively is crucial for storing and manipulating data in your R programs.
Creating Variables
Variables in R are used to store data values. You can create a variable by assigning a value to it using the assignment operator <-. You can also use the = operator, but <- is the preferred operator in R programming.
Example: Creating Variables
# Using the assignment operator x <- 10 # Using the equal operator y = 20 # Printing the values of variables print(x) # Output: 10 print(y) # Output: 20 Variable Naming Rules
When naming variables in R, you must follow these rules:
- Variable names must start with a letter (a-z, A-Z) or a period (.) followed by a letter.
- Variable names can contain letters, numbers (0-9), periods (.), and underscores (_).
- Variable names are case-sensitive (e.g.,
myVarandmyvarare different). - Avoid using reserved words (e.g.,
if,else,for, etc.) as variable names.
Example: Valid and Invalid Variable Names
# Valid variable names myVar <- 100 _my_var <- 200 my.var <- 300 myVar1 <- 400 # Invalid variable names # 1myVar <- 500 # Starts with a number # my-var <- 600 # Contains a hyphen # if <- 700 # Reserved word Checking Variable Type
You can check the type of a variable using the class() function.
Example: Checking Variable Type
# Creating variables of different types num_var <- 10.5 int_var <- 10L char_var <- "Hello, R!" bool_var <- TRUE # Checking the types of variables print(class(num_var)) # Output: "numeric" print(class(int_var)) # Output: "integer" print(class(char_var)) # Output: "character" print(class(bool_var)) # Output: "logical" Reassigning Variables
You can reassign variables to new values, even of a different type.
Example: Reassigning Variables
# Initial assignment x <- 10 print(x) # Output: 10 # Reassigning to a new value x <- "Hello, R!" print(x) # Output: "Hello, R!" Deleting Variables
You can delete a variable using the rm() function. Once deleted, the variable is no longer available in the current R session.
Example: Deleting Variables
# Creating a variable z <- 50 print(z) # Output: 50 # Deleting the variable rm(z) # Trying to print the deleted variable # print(z) # Error: object 'z' not found Example Program with Variables
Here is an example program that demonstrates the use of variables in R:
# R Program to Demonstrate Variables # Creating variables a <- 5 b <- 10 c <- a + b # Printing variables print(a) # Output: 5 print(b) # Output: 10 print(c) # Output: 15 # Reassigning variables a <- "R Programming" print(a) # Output: "R Programming" # Checking variable types print(class(a)) # Output: "character" print(class(b)) # Output: "numeric" # Deleting a variable rm(b) # Trying to print the deleted variable # print(b) # Error: object 'b' not found Conclusion
In this chapter, you learned about variables in R, including how to create, name, reassign, and delete them. Understanding how to use variables effectively is crucial for storing and manipulating data in your R programs. By following the rules for naming variables and knowing how to check their types, you can write clear and efficient R code.