Introduction to R and RStudio

Introduction

The R console

• Start by opening RStudio
• The pane on the left is the R console
• Note that each pane has multiple tabs

Using R as a calculator

• 2+2
• 2 + (incomplete)
• 2 + two (error)

Installing packages

• install.packages('tidyverse')
• check to makes sure everyone has it installed
• install from Tools menu

Getting help

• ?install.packages

Going beyond simple calculations in R

Variables

• a <- 2 (point out environment tab)
• a (print value)
• a+a
• b <- a + a
• b

Vectors

• u <- c(0, 0.25, 0.5, 0.75, 1)
• u
• u + 2
• u
• u <- u + 2 (then back up to original u)
• mean(u)
• v <- c(-1, 0, 1, 0, -1)
• u + v
• x <- seq(0, 1, by = 0.1)
• x
• ?seq

Basic plotting

• R typically creates plots from data
• If we want to plot \(y=x^2\) need to define vectors x and y with the data you want to plot
• y <- x^2
• y
• plot(x, y)
• plot(x, y, type = 'l')
• plot(x, y) then lines(x, y)
• can customize!

Working with data

• Check your working directory(folder):
• getwd()
• dir()
• We will be working primarily with the data that is already a part of a package but if you have data in a file, R will assume that it is located in this directory.
• Let us try to read into R a data file. Download a file from here. (Usually it will be downloaded into folder "Downloads" on your computer).
• Move or copy this file into R working directory
• Read this file:
• data_set <- read.csv('loan50.csv')
• Take a look at the data_set:
• data_set
• Now, let us access the same data as a part of 'openintro' package
• Install package 'openintro':
• install.packages('openintro')
• Load two installed packages into R:
• library('tidyverse')
• library('openintro')
• Take a look at the file loan50:
• loan50
• Note that it is presented differently, since 'loan50' dataset is being stored as a data frame. More about it later.

Intro to piping

• Try the following code:
• sum(3,2)
• Now try the piping:
• 3 |> sum(2)
• We can read the code as: “take 3 and pipe it into the sum() function. The pipe operator |> tells R to pass the object that comes before it into the first argument of the function that comes after it. Mathematically, x pipe f(y) becomes f(x, y), since x is piped into the first argument of the function f()
• Another way to pipe is to use operator %>%
• 3 %>% sum(2)
• You don't need to worry about all of the differences between |> and %>% at the moment but, in general, |> is a simplified version of %>%. For example, using %>% can be used to replace several arguments of a function: x %>% f(.,./2) becomes f(x,x/2)