Notes based on a reading of Emmanuel Paradis' R for Beginners

1.

Introduction

R is a language
Only objects in active memory are manipulated, not the data on the disk
Objects have attributes that specify what kind of data is represented
- 2 intrinsic attributes of all objects
  - mode and length

Basic syntax

a function is always written with parentheses, even if the are empty; e.g.getwd()
- A function without parentheses will display the content of the function
A value must be assigned to an object or it will not be stored in memory
ls() lists the objects in memory
Use the up arrow to scroll through previous commands
Regular sequences
- The : operator
- seq()
- c()
- rep()
- factor() & levels()

Installation

RStudio

Packages and importing

Basic language commands

Getting help

The on-line help can be accessed from within R with the use of ?; e.g. ?lm
- help(lm) and help('lm') are equivalent
- These commands only search packages that are loaded in memory. To search all packages, set try.all.packages = TRUE
For a more detailed desciption of what the is contained in the help documentation, see page 7 of https://cran.r-project.org/doc/contrib/Paradis-rdebuts_en.pdf

Example of a typical workflow

Plug slack & blog

#2.

Reading in data

Working with data

Basic read in is read.table()
Saving data
- write.table() or write() writes an objet in a file
- Can record a group of objects by making them into a 'workspace' with save(x, y, z, file= "xyz.RData")

Making lists, data frames, converting between them

Indexing and selecting

Indexing

Single brackets
- For example, to select the third value of vector x x[3]

Basics on objects

Types of data objects

Vector: one dimensional sequence of data elements
Matrix: a two-dimensional collection of data elements
- e.g.
Data frame: A two-dimensional collection of data elements where vectors must be of the same length but may be of different class
List: A collection of data elements that may be of different classes and lengths

3.

Plotting

4.

Control flow

5.

Functions

6.

Document creation