Introduction
Variables in R are used to store data values. R is a dynamically typed language, meaning you don't need to declare the type of a variable explicitly.
Creating Variables
# Using assignment operator
x <- 10
y <- "Hello"
z <- TRUE
# Also，可以使用 =
a = 25
Data Types in R
# Numeric
num <- 42.5
class(num)
# Integer
int <- as.integer(42)
class(int)
# Character (String)
char <- "R Programming"
class(char)
# Logical (Boolean)
logi <- TRUE
class(logi)
# Complex
comp <- 3 + 2i
class(comp)
Checking Data Types
# Check class
class(x)
# Check type
typeof(x)
# Check if numeric
is.numeric(x)
# Check if integer
is.integer(x)
# Check if character
is.character(x)
# Check if logical
is.logical(x)
Type Conversion
# Numeric to character
as.character(42)
# Character to numeric
as.numeric("42")
# Numeric to logical
as.logical(1) # TRUE
as.logical(0) # FALSE
# Logical to numeric
as.numeric(TRUE) # 1
as.numeric(FALSE) # 0
Special Values
# NA - Missing values
NA
# NULL - Empty object
NULL
# NaN - Not a Number
0/0
# Inf - Infinity
1/0
Variable Naming Rules
# Valid variable names
my_var <- 1
myVariable <- 2
.variable <- 3
my_variable_2 <- 4
# Invalid (will cause error)
# 2var <- 5 # Can't start with number
# my-var <- 6 # Can't use hyphen
Summary
Understanding variables and data types is fundamental to R programming. R's dynamic typing makes it flexible and easy to work with.