jonathanvoelkle · December 30, 2019 14:52
diff --git a/main.tex b/main.tex
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 % Define BibTeX command
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    T\kern-.1667em\lower.7ex\hbox{E}\kern-.125emX}}

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 \usepackage{makecell}
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 \begin{document}

 \setlength{\premulticols}{1pt}
 \setlength{\postmulticols}{1pt}
 \setlength{\multicolsep}{1pt}
 \setlength{\columnsep}{2em}

 \hspace{-2em}
 \begin{tabular}{l}
 	% \vspace{0cm}\epsfig{file=../licence/by-sa,width=24mm}\\
 \end{tabular}\vspace{-2mm}
 \hfill
 \hfill
 \Large{\textbf{R}}
 \hfill
 \hfill
 \scriptsize
 \today{} --- 
 \\
 \hrule~\\
 \raggedright
 \footnotesize
 \begin{multicols}{3}

 	Implementations are in \verb!.R! files, notebooks are in \verb!.Rmd!
 	files.\\
 	Everything after \verb!#! is seen as a comment by R.\\
 	R is case sensitive, and only \verb!A-Za-z0-9! should be used.\\
 	Commands are separated either by \verb!;! or a newline, and can be grouped by \verb!{!...\verb!}! \\
 	To quit the R programm the command is \verb!q()!

 	\subsection{Help}
 	\subsubsection{Accessing the help files}
 	\begin{tabular}{ll}
 		\verb!?mean!  & get help for particular function \\
 		\verb!help.search('weighted mean')! & search the help files            \\
 		\verb!help(package = 'MASS')! & find help for package
 	\end{tabular}

 	\subsubsection{More about a object}
 	\begin{tabular}{ll}
 		\verb!str(hills)! & get summary of objects structure    \\
 		\verb!class(hills)! & find the class an object belongs to
 	\end{tabular}

 	\subsection{Packages}
 	\begin{tabular}{ll}
 		\verb!install.packages('MASS')! & download and install a package \\
 		\verb!library(MASS)! & load the package into session, \\
 		                        & making its functions available \\
 		\verb!MASS::forbes! & using a function of a package  \\
 		\verb!data(hills)! & load a built-in dataset
 	\end{tabular}

 	\subsection{Working Directory}
 	\begin{tabular}{ll}
 		\verb!getwd()! & get the current working directory    \\
 		\verb!setwd('C://me/docs')! & change the current working directory
 	\end{tabular}

 	\subsection{Data types} % TODO
 	\begin{tabular}{lll}
 		\verb!logical! & Boolean, takes two values: \verb!TRUE! or \verb!FALSE! \\
 		\verb!numerix! & Has two modes, \verb!integer! and \verb!double! \\
 		\verb!complex! & \verb!1i! is used for \( i \) \\
 		\verb!character! & Are enterd using either \verb!'! or \verb!"!\\
 		% \verb!raw! & \\
 	\end{tabular}

 	\subsection{Data Structures}
 	R operates on \textit{data structures}, which are set by \verb!<-! or \verb!=!
 	\begin{tabular}{ll}
 		\verb!x <- c(10.9, 5.6, 6.4)! & combine three numbers to a vector
 	\end{tabular}

 	\subsection{Vectors}
 	\subsubsection{Creating Vectors}
 	\begin{tabular}{lll}
 		\verb!c(2,4,6)! & \verb!2 4 6! & join elements into vector \\
 		\verb!2:6! & \verb!2 3 4 5 6! & an integer sequence       \\
 		\verb!seq(2,3,by=0.5)! & \verb!2.0 2.5 3.0! & a double sequence         \\
 		\verb!rep(1:2, times=3)! & \verb!1 2 1 2 1 2! & repeat vector             \\
 		\verb!rep(1:2, each=3)! & \verb!1 1 1 2 2 2! & repeat elements of vector
 	\end{tabular}

 	\subsubsection{Vector Functions}
 	\begin{tabular}{ll}
 		\verb!sort(x)! & returns \verb!x! sorted   \\
 		\verb!table(x)! & see counts of values                     \\
 		\verb!rev(x)! & returns \verb!x! reversed \\
 		\verb!unique(x)! & see unique values                        \\
 	\end{tabular}

 	\subsubsection{Selecting Vector Elements}
 	\begin{tabular}{ll}
 		\verb!x[4]! & the fourth element                                  \\
 		\verb!x[-4]! & all but the fourth                                  \\
 		\verb!x[2:4]! & elements two to four                                \\
 		\verb!x[-(2:4)]! & all elements except two to four                     \\
 		\verb!x[c(1, 5)]! & elements one and five                               \\
    \verb!x[x == 10]! & elements which are equal to \verb!10! \\
 		\verb!x[x < 0]! & elements less than \verb!0!          \\
    \verb!which(x < 2)! & values of elements less than \verb!2! \\
 		\verb!x[x %in% c(1,2,5)]! & elemts that are in the set \verb!1,2,5!  \\
 		\verb!x['apple']! & element with name \verb!'apple'!
 	\end{tabular}

 	\subsection{Programming}
 	\subsubsection{For loop}
 	\begin{tabular}{ll}
 		for (variable in sequence) \{ & \verb!for (i in 1:4) {! \\
 		\quad do something            & \verb!  j <- i + 10 ! \\
 		\quad do more stuff           & \verb!  print(j)! \\
 		\}                            & \verb!}!
 	\end{tabular}

 	\subsubsection{While Loop}
 	\begin{tabular}{ll}
 		while (condition) \{ & \verb!while(i < 5) {! \\
 		\quad do something   & \verb!  print(i)! \\
 		\quad do more things & \verb!  i <- i + 1! \\
 		\}                   & \verb!}!
 	\end{tabular}

 	\subsubsection{If Statements}
 	\begin{tabular}{ll}
 		if (condition) \{            & \verb!if (i > 3) {! \\
 		\quad do something           & \verb!  print('Yes')! \\
 		\} else \{                   & \verb!} else {! \\
 		\quad do something different & \verb!  print('No')! \\
 		\}                           & \verb!}!
 	\end{tabular}

 	\subsubsection{Functions}
 	\begin{tabular}{ll}
 		function\_name <- function(var) \{ & \verb!square <- function (x) {! \\
 		\quad do something                 & \verb!  squared <- x*x! \\
 		\quad return (new\_variable)       & \verb!  return(squared)! \\
 		\}                                 & \verb!}!
 	\end{tabular}

 	\subsubsection{Conditions}
 	\begin{tabular}{ll}
 		\verb!a == b!     & Are equal             \\
 		\verb!a != b! & Not equal             \\
 		\verb!a > b!     & Greater than          \\
 		\verb!a < b!     & Less than             \\
 		\verb!a >= b!     & Greater than or equal \\
 		\verb!a <= b!     & Less than or equal    \\
 		\verb!is.na(a)!     & Is missing            \\
 		\verb!is.null(a)!     & In null
 	\end{tabular}

 	\subsection{Reading and Writing Data}
 	% See also \verb!readr! package \\
 	\begin{tabular}{ll}
 		\verb!df <- read.table('file.txt')! & Read and write                    \\
 		\verb!write.table(df, 'file.txt')! & \hfill a delimited text file      \\
 		\verb!df <- read.csv('file.csv')! & Read and write a                  \\
 		\verb!write.csv(df, 'file.txt')! & \hfill comma separated value file \\
 		\verb!load('file.Rdata')! & Read and write R data file        \\
 		\verb!save(df, file='file.Rdata')! & \hfill
 	\end{tabular}

 	\subsection{Types}
 	Converting between common data types in R. Can always go from a higher value in the table to a lower value
 	\begin{tabular}{lll}
 		\verb!as.logical(x)! & Boolean value \\
 		\verb!as.numeric(x)! & Integers of floating point numbers                                \\
 		\verb!as.charater(x)! & Character strings                                                 \\
 		\verb!as.factor(x)! & Character strings with preset levels.                             \\
 		                        & Needed for some statistical models                                \\
 	\end{tabular}
 	You can test if a element is of a given type using \verb!is.logical(x)!, \verb!is.integer(x)!, \verb!is.double(x)! and \verb!is.character(x)!. \verb!length(x)! determines the length, \verb!typeof(x)! the type of a vector

 	\subsection{Math Functions}
 	\begin{tabular}{ll}
 		\verb!1+2! & Addition                                              \\
 		\verb!2-3! & Subtraction                                           \\
 		\verb!3*4! & Multiplication                                        \\
 		\verb!4/5! & Division                                              \\
 		\verb!5%/%6! & Integer divison                                       \\
 		\verb!6^7! & Exponentiation                                        \\
 		\verb!7%%8! & Modulus                                               \\
 		\verb!sqrt(x)! & Square root                                           \\
 		\verb!floor(x)! & Floor function                                        \\
 		\verb!log(x)! & Natural log                                           \\
 		\verb!exp(x)! & Exponential                                           \\
 		\verb!sin(x)! & Sinus function                                        \\
 		\verb!max(x)! & Largest element                                       \\
 		\verb!min(x)! & Smallest element                                      \\
 		\verb!round(x, n)! & Round to \verb!n! decimal places      \\
 		\verb!signif(x, n)! & Round to \verb!n! significant figures \\
 		\verb!cor(x, y)! & Correlation                                           \\
 		\verb!sum(x)! & Sum                                                   \\
    \verb!cumsum(x)! & Cumulative sum \\
    \verb!prod(x)! & Product \\
 		\verb!mean(x)! & Mean                                                  \\
 		\verb!median(x)! & Median                                                \\
 		\verb!quantile(x)! & Percentage quantiles                                  \\
 		\verb!rank(x)! & Rank of elements                                      \\
 		\verb!var(x)! & The variance                                          \\
 		\verb!sd(x)! & The standard deviation
 	\end{tabular}


 	\subsection{Variable Assignment}
 	\begin{tabular}{l}
 		\verb!> a <- 'apple'! \\
 		\verb!> a! \\
 		\verb![1] 'apple'!
 	\end{tabular}

 	\subsection{The Environment}
 	\begin{tabular}{ll}
 		\verb!ls()! & List all the variables in the environment            \\
 		\verb!rm(x)! & Remove \verb!x! from the environment \\
 		\verb!rm(list = ls())! & Remove all variables from the environment
 	\end{tabular}

 	\subsection{Matrices}
 	\verb!m <- matrix(x, nrow=3, ncol=3)! \ Create a matrix from \verb!x!
 	\begin{tabular}{ll}
 		\verb!m[2,  ]! & Select the second row                         \\
 		\verb!m[ , 1]! & Select the second column                      \\
 		\verb!m[2, 3]! & Select the second element in the third column \\
 		\verb!t(m)! & Transpose                                     \\
 		\verb!m %*% n! & Matrix mulitplication                         \\
    \verb!solve(m, n)! & Find \(x\) in \(m*x=n\) \\
    \verb!m.inv! & Inverts matrix 
 	\end{tabular}

 	\subsection{Lists}
 	\verb!l <- list(x=1:5, y=c('a','b')! A list is a collection of elements which can be of different types
 	\begin{tabular}{ll}
 		\verb!l[[2]]! & Second element of l                  \\
 		\verb!l[1]! & New list with only the first element \\
 		\verb!l$x! & Elements named x                     \\
 		\verb!l['y']! & New list with only element named y
 	\end{tabular}

 	\subsection{Data Frames}
 	% See also \verb!dplyr! package \\
 	\verb!df <- data.frame(x=1:3, y=c('a','b'))! A special case of a list where all elements are the same length \\
 	Both the matrix and list subsetting can be used \\
 	\begin{tabular}{ll}
 		\verb!View(df)! & See the full data frame    \\
 		\verb!head(df)! & See the first 6 rows       \\
 		\verb!nrow(df)! & Number of rows             \\
 		\verb!ncol(df)! & Number of columns          \\
 		\verb!dim(df)! & Number of columns and rows \\
 		\verb!cbind()! & Bind columns                       \\
 		\verb!rbind()! & Bind rows
 	\end{tabular}

 	\subsection{Strings}
 	% Also see the \verb!stringr! package \\
 	\begin{tabular}{ll}
 		\verb!paste(x, y, sep=' ')! & Join multiple vectors together       \\
 		\verb!paste(x, collapse=' ')! & Join elements of a vector together   \\
 		\verb!grep(regex, x)! & Find regular expression matches in x \\
 		\verb!gsub(regex, repl, x)! & Replace matches in x with a string   \\
 		\verb!toupper(x)! & Convert to uppercase                 \\
 		\verb!tolower(x)! & Convert to lowercase                 \\
 		\verb!nchar(x)! & Number of characters in a string
 	\end{tabular}

 	\subsection{Factors}
 	\begin{tabular}{ll}
    \verb!factor(x)! & Turn a vector into a factor. Can set the \\
                    & levels of the factor and the order \\
    \verb!cut(x, breaks=4)! & Turn a numeric vector into a \\
                          & factor by `cutting' into sections
 	\end{tabular}

 	\subsection{Statisics}
 	\begin{tabular}{ll}
 		\verb!lm(y ~ x, data=df)! & Linear model                                    \\
 		\verb!glm(y ~ x, data=df)! & Generalised linear model                        \\
 		\verb!summary! & Get more detailed information out a model       \\
 		\verb!t.test(x, y)! & Perform a t-test for a difference between means \\
 		\verb!pairwise.t.test! & Perform a t-test for a paired data              \\
 		\verb!prop.test! & Test for a difference between proportions       \\
 		\verb!aov! & Analysis of the variance
 	\end{tabular}

 	\subsection{Distributions}
 	\begin{tabular}{lcccc}
 		         & \makecell{Random \\ Variates} & \makecell{Density \\ Function} & \makecell{Cumulative \\ Distribution} & \makecell{Quantile}             \\
 		Normal   & \verb!pnorm! & \verb!dnorm! & \verb!pnorm! & \verb!qnorm! \\
 		Poisson  & \verb!rpois! & \verb!dpois! & \verb!ppois! & \verb!qpois! \\
 		Binomial & \verb!rbinom! & \verb!dbinom! & \verb!pbinom! & \verb!qbinom! \\
 		Uniform  & \verb!runif! & \verb!dunif! & \verb!punif! & \verb!qunif!
 	\end{tabular}

 	\subsection{Plotting}
 	\begin{tabular}{ll}
 		\verb!plot(x)! & Values of x in order  \\
 		\verb!plot(x, y)! & Values of x against y \\
 		\verb!hist(x)! & Histogramm of x
 	\end{tabular}

 \end{multicols}


 \end{document}

 \subsection{Misc}
	\documentclass[10pt,landscape]{article}
	\usepackage{multicol}
	\usepackage{calc}
	\usepackage{ifthen}
	\usepackage[landscape]{geometry}
	\usepackage{epsfig}

	\ifthenelse{\lengthtest { \paperwidth = 11in}}
	{ \geometry{top=.5in,left=.5in,right=.5in,bottom=.5in} }
	{\ifthenelse{ \lengthtest{ \paperwidth = 297mm}}
	{\geometry{top=1cm,left=1cm,right=1cm,bottom=1cm} }
	{\geometry{top=1cm,left=1cm,right=1cm,bottom=1cm} }
	}
	\pagestyle{empty}
	\makeatletter
	\renewcommand{\section}{\@startsection{section}{1}{0mm}%
	{-1ex plus -.5ex minus -.2ex}%
	{0.5ex plus .2ex}%x
	{\normalfont\large\bfseries}}
	\renewcommand{\subsection}{\@startsection{subsection}{2}{0mm}%
	{-1explus -.5ex minus -.2ex}%
	{0.5ex plus .2ex}%
	{\normalfont\normalsize\bfseries}}
	\renewcommand{\subsubsection}{\@startsection{subsubsection}{3}{0mm}%
	{-1ex plus -.5ex minus -.2ex}%
	{1ex plus .2ex}%
	{\normalfont\small\bfseries}}
	\makeatother

	% Define BibTeX command
	\def\BibTeX{{\rm B\kern-.05em{\sc i\kern-.025em b}\kern-.08em
	T\kern-.1667em\lower.7ex\hbox{E}\kern-.125emX}}

	% Don't print section numbers
	\setcounter{secnumdepth}{0}


	\setlength{\parindent}{0pt}
	\setlength{\parskip}{0pt plus 0.5ex}


	% -----------------------------------------------------------------------

	\usepackage{makecell}
	\setlength{\tabcolsep}{1ex}

	% -----------------------------------------------------------------------

	\begin{document}

	\setlength{\premulticols}{1pt}
	\setlength{\postmulticols}{1pt}
	\setlength{\multicolsep}{1pt}
	\setlength{\columnsep}{2em}

	\hspace{-2em}
	\begin{tabular}{l}
	% \vspace{0cm}\epsfig{file=../licence/by-sa,width=24mm}\\
	\end{tabular}\vspace{-2mm}
	\hfill
	\hfill
	\Large{\textbf{R}}
	\hfill
	\hfill
	\scriptsize
	\today{} ---
	\\
	\hrule~\\
	\raggedright
	\footnotesize
	\begin{multicols}{3}

	Implementations are in \verb!.R! files, notebooks are in \verb!.Rmd!
	files.\\
	Everything after \verb!#! is seen as a comment by R.\\
	R is case sensitive, and only \verb!A-Za-z0-9! should be used.\\
	Commands are separated either by \verb!;! or a newline, and can be grouped by \verb!{!...\verb!}! \\
	To quit the R programm the command is \verb!q()!

	\subsection{Help}
	\subsubsection{Accessing the help files}
	\begin{tabular}{ll}
	\verb!?mean! & get help for particular function \\
	\verb!help.search('weighted mean')! & search the help files \\
	\verb!help(package = 'MASS')! & find help for package
	\end{tabular}

	\subsubsection{More about a object}
	\begin{tabular}{ll}
	\verb!str(hills)! & get summary of objects structure \\
	\verb!class(hills)! & find the class an object belongs to
	\end{tabular}

	\subsection{Packages}
	\begin{tabular}{ll}
	\verb!install.packages('MASS')! & download and install a package \\
	\verb!library(MASS)! & load the package into session, \\
	& making its functions available \\
	\verb!MASS::forbes! & using a function of a package \\
	\verb!data(hills)! & load a built-in dataset
	\end{tabular}

	\subsection{Working Directory}
	\begin{tabular}{ll}
	\verb!getwd()! & get the current working directory \\
	\verb!setwd('C://me/docs')! & change the current working directory
	\end{tabular}

	\subsection{Data types} % TODO
	\begin{tabular}{lll}
	\verb!logical! & Boolean, takes two values: \verb!TRUE! or \verb!FALSE! \\
	\verb!numerix! & Has two modes, \verb!integer! and \verb!double! \\
	\verb!complex! & \verb!1i! is used for \( i \) \\
	\verb!character! & Are enterd using either \verb!'! or \verb!"!\\
	% \verb!raw! & \\
	\end{tabular}

	\subsection{Data Structures}
	R operates on \textit{data structures}, which are set by \verb!<-! or \verb!=!
	\begin{tabular}{ll}
	\verb!x <- c(10.9, 5.6, 6.4)! & combine three numbers to a vector
	\end{tabular}

	\subsection{Vectors}
	\subsubsection{Creating Vectors}
	\begin{tabular}{lll}
	\verb!c(2,4,6)! & \verb!2 4 6! & join elements into vector \\
	\verb!2:6! & \verb!2 3 4 5 6! & an integer sequence \\
	\verb!seq(2,3,by=0.5)! & \verb!2.0 2.5 3.0! & a double sequence \\
	\verb!rep(1:2, times=3)! & \verb!1 2 1 2 1 2! & repeat vector \\
	\verb!rep(1:2, each=3)! & \verb!1 1 1 2 2 2! & repeat elements of vector
	\end{tabular}

	\subsubsection{Vector Functions}
	\begin{tabular}{ll}
	\verb!sort(x)! & returns \verb!x! sorted \\
	\verb!table(x)! & see counts of values \\
	\verb!rev(x)! & returns \verb!x! reversed \\
	\verb!unique(x)! & see unique values \\
	\end{tabular}

	\subsubsection{Selecting Vector Elements}
	\begin{tabular}{ll}
	\verb!x[4]! & the fourth element \\
	\verb!x[-4]! & all but the fourth \\
	\verb!x[2:4]! & elements two to four \\
	\verb!x[-(2:4)]! & all elements except two to four \\
	\verb!x[c(1, 5)]! & elements one and five \\
	\verb!x[x == 10]! & elements which are equal to \verb!10! \\
	\verb!x[x < 0]! & elements less than \verb!0! \\
	\verb!which(x < 2)! & values of elements less than \verb!2! \\
	\verb!x[x %in% c(1,2,5)]! & elemts that are in the set \verb!1,2,5! \\
	\verb!x['apple']! & element with name \verb!'apple'!
	\end{tabular}

	\subsection{Programming}
	\subsubsection{For loop}
	\begin{tabular}{ll}
	for (variable in sequence) \{ & \verb!for (i in 1:4) {! \\
	\quad do something & \verb! j <- i + 10 ! \\
	\quad do more stuff & \verb! print(j)! \\
	\} & \verb!}!
	\end{tabular}

	\subsubsection{While Loop}
	\begin{tabular}{ll}
	while (condition) \{ & \verb!while(i < 5) {! \\
	\quad do something & \verb! print(i)! \\
	\quad do more things & \verb! i <- i + 1! \\
	\} & \verb!}!
	\end{tabular}

	\subsubsection{If Statements}
	\begin{tabular}{ll}
	if (condition) \{ & \verb!if (i > 3) {! \\
	\quad do something & \verb! print('Yes')! \\
	\} else \{ & \verb!} else {! \\
	\quad do something different & \verb! print('No')! \\
	\} & \verb!}!
	\end{tabular}

	\subsubsection{Functions}
	\begin{tabular}{ll}
	function\_name <- function(var) \{ & \verb!square <- function (x) {! \\
	\quad do something & \verb! squared <- x*x! \\
	\quad return (new\_variable) & \verb! return(squared)! \\
	\} & \verb!}!
	\end{tabular}

	\subsubsection{Conditions}
	\begin{tabular}{ll}
	\verb!a == b! & Are equal \\
	\verb!a != b! & Not equal \\
	\verb!a > b! & Greater than \\
	\verb!a < b! & Less than \\
	\verb!a >= b! & Greater than or equal \\
	\verb!a <= b! & Less than or equal \\
	\verb!is.na(a)! & Is missing \\
	\verb!is.null(a)! & In null
	\end{tabular}

	\subsection{Reading and Writing Data}
	% See also \verb!readr! package \\
	\begin{tabular}{ll}
	\verb!df <- read.table('file.txt')! & Read and write \\
	\verb!write.table(df, 'file.txt')! & \hfill a delimited text file \\
	\verb!df <- read.csv('file.csv')! & Read and write a \\
	\verb!write.csv(df, 'file.txt')! & \hfill comma separated value file \\
	\verb!load('file.Rdata')! & Read and write R data file \\
	\verb!save(df, file='file.Rdata')! & \hfill
	\end{tabular}

	\subsection{Types}
	Converting between common data types in R. Can always go from a higher value in the table to a lower value
	\begin{tabular}{lll}
	\verb!as.logical(x)! & Boolean value \\
	\verb!as.numeric(x)! & Integers of floating point numbers \\
	\verb!as.charater(x)! & Character strings \\
	\verb!as.factor(x)! & Character strings with preset levels. \\
	& Needed for some statistical models \\
	\end{tabular}
	You can test if a element is of a given type using \verb!is.logical(x)!, \verb!is.integer(x)!, \verb!is.double(x)! and \verb!is.character(x)!. \verb!length(x)! determines the length, \verb!typeof(x)! the type of a vector

	\subsection{Math Functions}
	\begin{tabular}{ll}
	\verb!1+2! & Addition \\
	\verb!2-3! & Subtraction \\
	\verb!3*4! & Multiplication \\
	\verb!4/5! & Division \\
	\verb!5%/%6! & Integer divison \\
	\verb!6^7! & Exponentiation \\
	\verb!7%%8! & Modulus \\
	\verb!sqrt(x)! & Square root \\
	\verb!floor(x)! & Floor function \\
	\verb!log(x)! & Natural log \\
	\verb!exp(x)! & Exponential \\
	\verb!sin(x)! & Sinus function \\
	\verb!max(x)! & Largest element \\
	\verb!min(x)! & Smallest element \\
	\verb!round(x, n)! & Round to \verb!n! decimal places \\
	\verb!signif(x, n)! & Round to \verb!n! significant figures \\
	\verb!cor(x, y)! & Correlation \\
	\verb!sum(x)! & Sum \\
	\verb!cumsum(x)! & Cumulative sum \\
	\verb!prod(x)! & Product \\
	\verb!mean(x)! & Mean \\
	\verb!median(x)! & Median \\
	\verb!quantile(x)! & Percentage quantiles \\
	\verb!rank(x)! & Rank of elements \\
	\verb!var(x)! & The variance \\
	\verb!sd(x)! & The standard deviation
	\end{tabular}


	\subsection{Variable Assignment}
	\begin{tabular}{l}
	\verb!> a <- 'apple'! \\
	\verb!> a! \\
	\verb![1] 'apple'!
	\end{tabular}

	\subsection{The Environment}
	\begin{tabular}{ll}
	\verb!ls()! & List all the variables in the environment \\
	\verb!rm(x)! & Remove \verb!x! from the environment \\
	\verb!rm(list = ls())! & Remove all variables from the environment
	\end{tabular}

	\subsection{Matrices}
	\verb!m <- matrix(x, nrow=3, ncol=3)! \ Create a matrix from \verb!x!
	\begin{tabular}{ll}
	\verb!m[2, ]! & Select the second row \\
	\verb!m[ , 1]! & Select the second column \\
	\verb!m[2, 3]! & Select the second element in the third column \\
	\verb!t(m)! & Transpose \\
	\verb!m %*% n! & Matrix mulitplication \\
	\verb!solve(m, n)! & Find \(x\) in \(m*x=n\) \\
	\verb!m.inv! & Inverts matrix
	\end{tabular}

	\subsection{Lists}
	\verb!l <- list(x=1:5, y=c('a','b')! A list is a collection of elements which can be of different types
	\begin{tabular}{ll}
	\verb!l[[2]]! & Second element of l \\
	\verb!l[1]! & New list with only the first element \\
	\verb!l$x! & Elements named x \\
	\verb!l['y']! & New list with only element named y
	\end{tabular}

	\subsection{Data Frames}
	% See also \verb!dplyr! package \\
	\verb!df <- data.frame(x=1:3, y=c('a','b'))! A special case of a list where all elements are the same length \\
	Both the matrix and list subsetting can be used \\
	\begin{tabular}{ll}
	\verb!View(df)! & See the full data frame \\
	\verb!head(df)! & See the first 6 rows \\
	\verb!nrow(df)! & Number of rows \\
	\verb!ncol(df)! & Number of columns \\
	\verb!dim(df)! & Number of columns and rows \\
	\verb!cbind()! & Bind columns \\
	\verb!rbind()! & Bind rows
	\end{tabular}

	\subsection{Strings}
	% Also see the \verb!stringr! package \\
	\begin{tabular}{ll}
	\verb!paste(x, y, sep=' ')! & Join multiple vectors together \\
	\verb!paste(x, collapse=' ')! & Join elements of a vector together \\
	\verb!grep(regex, x)! & Find regular expression matches in x \\
	\verb!gsub(regex, repl, x)! & Replace matches in x with a string \\
	\verb!toupper(x)! & Convert to uppercase \\
	\verb!tolower(x)! & Convert to lowercase \\
	\verb!nchar(x)! & Number of characters in a string
	\end{tabular}

	\subsection{Factors}
	\begin{tabular}{ll}
	\verb!factor(x)! & Turn a vector into a factor. Can set the \\
	& levels of the factor and the order \\
	\verb!cut(x, breaks=4)! & Turn a numeric vector into a \\
	& factor by `cutting' into sections
	\end{tabular}

	\subsection{Statisics}
	\begin{tabular}{ll}
	\verb!lm(y ~ x, data=df)! & Linear model \\
	\verb!glm(y ~ x, data=df)! & Generalised linear model \\
	\verb!summary! & Get more detailed information out a model \\
	\verb!t.test(x, y)! & Perform a t-test for a difference between means \\
	\verb!pairwise.t.test! & Perform a t-test for a paired data \\
	\verb!prop.test! & Test for a difference between proportions \\
	\verb!aov! & Analysis of the variance
	\end{tabular}

	\subsection{Distributions}
	\begin{tabular}{lcccc}
	& \makecell{Random \\ Variates} & \makecell{Density \\ Function} & \makecell{Cumulative \\ Distribution} & \makecell{Quantile} \\
	Normal & \verb!pnorm! & \verb!dnorm! & \verb!pnorm! & \verb!qnorm! \\
	Poisson & \verb!rpois! & \verb!dpois! & \verb!ppois! & \verb!qpois! \\
	Binomial & \verb!rbinom! & \verb!dbinom! & \verb!pbinom! & \verb!qbinom! \\
	Uniform & \verb!runif! & \verb!dunif! & \verb!punif! & \verb!qunif!
	\end{tabular}

	\subsection{Plotting}
	\begin{tabular}{ll}
	\verb!plot(x)! & Values of x in order \\
	\verb!plot(x, y)! & Values of x against y \\
	\verb!hist(x)! & Histogramm of x
	\end{tabular}

	\end{multicols}


	\end{document}

	\subsection{Misc}