R is designed for Data Analysis, Statistics, and Visualization. It emphasizes working with vectors, data frames, and lists, and provides powerful tools for analysis and report writing.

This guide introduces the fundamental syntax and usage of R.

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. We will talk more about this later.

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

Starts with #

# This is a comment

print("This code will execute!")

Multi-line Programs

to write Multi-line Programs we can use the %>% symbol between commands.


Example <- Print("Here is line 1") %>%
           var <- ("Here is line 2") %>%
           Print(var)

print(Example)

This would return:


here is line 1
Here is line 2

Variables

Variables store values of different data types and are assigned using <- (recommended) or =.

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

Variable Naming Rules

There are certain rules to follow to not mess up your variable assignments

Don’t include special characters in your variable assignments

don't_do_this! <- "please"

Don’t start variable assignments with numbers.

3_favorite_things <- ('movies, candy, family')

We want our variable names to start with characters.


three_favorite_things <- ('movies, candy, family')

Basic Data Types

There are a few general data types that will help you work with data in countless ways.

Character (Strings)

message <- "Hello"

Numeric

temperature <- 98.6

Logical (Boolean)

is_active <- TRUE

Printing Output

Use print() with a “string”, or with the variable name.

print("Hello World")

greeting <- "Hello Alice"
print(greeting)

#This will return: Hello Alice

number <- 22
print(number)

#This will return: 22

test <- TRUE
print(test == TRUE)

#This will return: TRUE

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)

Using these commands will be important when Cleaning large datasets.

Operators

R supports a wide range of operators.

Arithmetic Operators

R supports standard Mathematical Operations. These allow you to compute mathmatic operations on your data.

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

Comparison Operators

These are used to Compare Values of different variables, they are commonly used when using Conditional Statements, which we will talk about later.

x <- 10
y <- 5

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

Conditional Statements

Conditional Statements control program flow.

if statements

If statements Evaluate a Condition, and then provide an appropriate output based on if that condition is True or False

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

if else statements

These statements will evaluate if a condition is True or False and will provide statement for both options.

age <- 18
 if (age >= 18) {
   print("You are an adult")
} else {
   print("you are not an adult")
 }

else if statments

These statements will allow for Multiple Different conditional statements to be evaluated.

age <- 18
 if (age >= 18) {
   print("You are an adult")
} else if (13 < age < 18) {
  print("You are a teenager")
}
else {
   print("you are a child")
 }

Loops

Loops will Cycle Through a set Range of Values and run a program for every iteration.

For Loop

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

# This loop will print the numbers 1-5.

While Loop

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

Both of these loops are effective for iterating through a set number. However, for loops are commonly better used with multiple datasets, as you don’t need to know the number of iterations you want.

Data formats

There are multiple different data formats that you will come across.

Vectors

Vectors are series of data such as Numbers,Strings, and Characters

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

# We can call the number 1 with this command 

print(numbers[1])

Matrices

Matrices can be thought of as a Two Dimensional Vector.


#to make a matrix, we can assign our numbers of rows and columns to set our 
dimensions 

numbers <- matrix (c(1,2,3,4,5,6,7,8,9), nrow = 3, ncol = 3)

Lists

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

Data Frames

Data Frames allow us to make a set of data similar to a matrix.


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

Functions

Functions allow us to Take in User Input and provide an outcome based on that input. These are largely applicable among all coding languages and are benfical to familiarize yourself with.

The main benefit of functions is that we are able to make what would be long and tedious scripts; into much shorter and concise lines of code.

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

greet("Alice")

Installing and Loading Packages

Packages are a Series of Commands and Programs that are made outside of base R, commonly by developers and others.

They Allow us to Perform Operations Beyond the Capabilities of Base R as well as simplifying actions that would otherwise be complex and tedious.

One example is ggplot2, a library that is important for Creating Data Visualizations.

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

Package and Function Information

The Help Command is one of the most useful tools in R. Running this command will allow you to view all Information about a specific R commmand.

help(print)

#This command will return a full resource page of how to use the print command as well as examples

Writing Your First Script

Lets look at an example of creating a script that returns someones name. Try it out on your r console!

if we have a file named hello.R, we can make the following script in it.

greetings <- function(name) {

name = readline("Enter your name here")
if (nchar(name) > 0) {
  print(paste("Hello", name))
} else {
  print("Hello stranger")
}
}

Run from command line, or press CTRL + Enter to run your script:

Rscript hello.R
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