Introduction to R - Data Literacy

Version 1.8 - July 2024

Workshop 1 - Part 2 - Basics

So R is…?

Briefly, R is

a programming language.
borne out of statistics but thanks to many open-source extension packages is a very useful tool for working with data.
named after S - another programming language which the creators of R were inspired by.

R is used by executing statements of the R programming language, or code, commonly at a command line or in a notebook in RStudio or a Jupyter Notebook. RStudio is a dedicated Integrated Development Environment (IDE) utilising a Graphical User Interface (GUI), and also provides package installation, output document and website generation, file management and many other aspects of working with R.

Whilst R is an ‘interpreted language’, many of the extension packages are ‘compiled’, which makes them seriously fast and powerful for processing data.

Let’s begin

Simple mathematics is possible with R. Much like a calculator.

Let’s start with the following code. Execute the code by using the keyboard shortcut Ctrl+Enter (Command+Enter on a Mac).

1 + 1

## [1] 2

The output response from R will appear below the executed code.

Hopefully the answer 2 appeared below the code. The code can be typed over and re-executed again. (Try changing the code above, perhaps to 2 + 3 for example, and re-execute to observe the changed output).

All sorts of maths is possible, including a variety of functions similar to those available on a calculator.

Try the following one at a time (or all together).

( 5 * 6 ) + 12

## [1] 42

6^2 + 6

## [1] 42

sqrt(49) * mean(1:11) * sin(pi/2)

## [1] 42

Note. Trig functions are in radians. The colon : operator returns a number series between the two numbers.

Variables

Variables are at the heart of coding. Variables are placeholders for sets of data, and allow shorthand style code statements to powerfully manipulate data, repeatedly as required.

In R, the symbol ‘<-’ is used to assign a variable a value rather than ‘=’. We’ll skip the discussion about why in this introduction. The keyboard shortcut is Alt + -, or Option + - on a Mac.

To see the value of a variable, simply execute the variable name, or use print().

For example, lets assign the variable integer1 with the integer value 42 and then print it.

integer1 <- 42
integer1

## [1] 42

Try the following to explore some common variable data types and structures.

string1 <- "forty two"
string1

## [1] "forty two"

vector_integer1 <- c(1:5,11:15)
vector_integer1

##  [1]  1  2  3  4  5 11 12 13 14 15

vector_string1 <- c("apples","oranges","lemons") 
vector_string1

## [1] "apples"  "oranges" "lemons"

list_string1 <- list("apples","oranges","lemons") 
list_string1

## [[1]]
## [1] "apples"
## 
## [[2]]
## [1] "oranges"
## 
## [[3]]
## [1] "lemons"

data_frame1 <- data.frame(fruit=c("apples","oranges","lemons"),
                                   quantity=c(7,14,21))
data_frame1

##     fruit quantity
## 1  apples        7
## 2 oranges       14
## 3  lemons       21

Preflight

The next steps in this workflow need the following libraries/packages to extend the capabilities of base R. The code can be copy and pasted! R will return a number of messages related to loading these libraries, they can be helpful when developing workflows and can be suppressed when no longer required.

if(!require(tidyverse)){
    install.packages("tidyverse")
    library(tidyverse)
}  
if(!require(readxl)){
    install.packages("readxl")
    library(readxl)
}
if(!require(plotly)){
    install.packages("plotly")
    library(plotly)
}
if(!require(sf)){
    install.packages("sf")
    library(sf)
}  
if(!require(rmapshaper)){
    install.packages("rmapshaper")
    library(rmapshaper)
}
if(!require(leaflet)){
    install.packages("leaflet")
    library(leaflet)
}
if(!require(htmltools)){
    install.packages("htmltools")
    library(htmltools)
}
if(!require(crosstalk)){
    install.packages("crosstalk")
    library(crosstalk)
}
if(!require(RSQLite)){
    install.packages("RSQLite")
    library(RSQLite)
}
if(!require(jsonlite)){
    install.packages("jsonlite")
    library(jsonlite)
}

Sample Data in R

Data in tabular format, or tables, is a very common starting point when working with data.

R includes some sample data sets to work with whilst exploring R. One such data set is called mtcars, which has various features for 32 now ancient cars from a 1974 survey for a US car magazine.

head(mtcars, 5)

##                    mpg cyl disp  hp drat    wt  qsec vs am gear carb
## Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
## Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
## Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
## Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
## Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2

Running this head() command will give a stylised table consisting of all columns for the first five rows of data.

Part 1 - Introduction

Part 3 - Real world data analysis and visualisation