R is designed for data analysis, statistics, and visualization. It emphasizes working with data structures like vectors, data frames, and lists, and provides powerful tools for analysis and reporting.

This guide introduces the fundamental syntax used in R programs.

Running R

You can run R in several ways, with the simplest being via the command line or the interactive R console.

Interactive R Console

Windows

Open the Command Prompt and type:

R

macOS

Open the Terminal and type:

R

You can also use RStudio, a popular integrated development environment (IDE) for working with R.

R Syntax

Practice writing and executing the following using the R console.
To execute a line of code, press the Enter key.

Note: to exit the R console write and execute quit()

Comments

Comments are ignored by R and help explain your code.

Single Line Comment

Starts with #

# This is a comment
print("This code will execute!")

Variables

Variables store values and are assigned using <- (recommended) or =.

name <- "Alice"
age <- 30
height <- 5.6

Basic Data Types

Character (Strings)

message <- "Hello"

Numeric

count <- 10
temperature <- 98.6

Logical (Boolean)

is_active <- TRUE

Printing Output

Use print() or simply type the variable name.

print("Hello World")

name <- "Alice"
print(paste("Hello", name))

User Input

R can accept user input using readline().

name <- readline(prompt = "Enter your name: ")
print(paste("Hello", name))

Type Conversion

Convert between data types using built-in functions.

Function Purpose —————— ——————– as.integer() convert to integer as.numeric() convert to numeric as.character() convert to string

age <- as.integer("30")
temperature <- as.numeric("98.6")
number <- as.character(42)

Arithmetic Operators

R supports standard mathematical operations.

a <- 10
b <- 3

a + b
a - b
a * b
a / b
a^b
a %% b

Comparison Operators

Used to compare values.

x <- 10
y <- 5

x > y
x < y
x == y
x != y

Conditional Statements

Conditional statements control program flow.

age <- 18
if (age >= 18) {
  print("You are an adult")
}

Loops

For Loop

for (i in 1:5) {
  print(i)
}

While Loop

count <- 0
while (count < 5) {
  print(count)
  count <- count + 1
}

Vectors

numbers <- c(1, 2, 3, 4, 5)
numbers[1]

Lists

my_list <- list(name = "Alice", age = 30, active = TRUE)

Data Frames

df <- data.frame(
  name = c("Alice", "Bob"),
  age = c(25, 30)
)

print(df)

Functions

greet <- function(name) {
  print(paste("Hello", name))
}

greet("Alice")

Installing and Loading Packages

install.packages("ggplot2")
library(ggplot2)

Writing Your First Script

name <- readline(prompt = "What is your name? ")

if (nchar(name) > 0) {
  print(paste("Hello", name))
} else {
  print("Hello stranger")
}

Run from command line:

Rscript hello.R
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