• Lectures followed by practicals
• Materials are on the homepage
  • “Impracticals” are the versions without solutions, “Practicals” the ones with
• Please do ask questions

• R is a language and environment for statistical computing and for graphics

• GNU project (100% free software)

• Managed by the R Foundation for Statistical Computing, Vienna, Austria.

• Community-driven

• Based on the object-oriented language S (1975)

• Aggregates all convenient information and procedures into one single place
• Allows you to work in projects
• Manages your code with highlighting
• Gives extra functionality (Shiny, knitr, markdown, LaTeX)
• Allows for integration with version control routines, such as Git.

• Huge, active, welcoming online community
  • #rstats
  • rweekly
  • rbloggers
  • Stack Overflow
• Package development
  • About eight packages supplied with base R
  • More than 15.000 packages on CRAN

• Everything that is published CRAN and is aimed at R users, must be accompanied by a help file.
• If you know the name of the function that performs an operation, e.g. anova(), then you just type ?anova or help(anova) in the console.
• If you do not know the name of the function: type ?? followed by your search criterion. For example ??anova returns a list of all help pages that contain the word ‘anova’

• Write commands directly in the console
• Or write code in the editor and submit with Ctrl + Enter
• Assign values to objects with <-

a <- c(1, 8, 42, pi, 2^3, 1)
b <- 0:5
c <- rep( c("Hi", "there"), 3)
D <- as.data.frame(cbind(a,b,c))

Vectors and character vectors

c(1,2,3,4,5)

## [1] 1 2 3 4 5

1:5

## [1] 1 2 3 4 5

as.character(1:5)

## [1] "1" "2" "3" "4" "5"

Matrices

matrix(1:12, nrow = 3)

##      [,1] [,2] [,3] [,4]
## [1,]    1    4    7   10
## [2,]    2    5    8   11
## [3,]    3    6    9   12

The elements of a vector or matrix must all have the same type

Data sets for R

D <- as.data.frame(cbind(a,b,c))
D

##                  a b     c
## 1                1 0    Hi
## 2                8 1 there
## 3               42 2    Hi
## 4 3.14159265358979 3 there
## 5                8 4    Hi
## 6                1 5 there

Alternatively: tibbles or data.tables

D[1,3]

## [1] Hi
## Levels: Hi there

D[1,]

##   a b  c
## 1 1 0 Hi

D[,2]

## [1] 0 1 2 3 4 5
## Levels: 0 1 2 3 4 5

The tidyverse is a collection of packages that “share an underlying design philosophy, grammar, and data structures”. They make for easier data handling and visualization.

The pipe %>% allows for chained method calls that make code much more readable

library(dplyr)

## Warning: package 'dplyr' was built under R version 3.6.1

starwars %>%
  subset( species == "Human" ) %>%
  group_by( homeworld ) %>% 
  summarise( n = n(), mean.height = mean(height))

library(ggplot2)
starwars %>% ggplot( aes( x = height)) + geom_histogram()