The function shortlist below is far from complete because R has more to offer, but it lists the functions discussed in this Beginner's Guide to R.

RStudio - General

• setwd(dir=...)
• getwd()
• instal.packages()
• library()
• vignette()
• rm()
• read.table(file=…, header=…, sep=…, dec=…)
• write.table(…, file=…, sep=…, quote=…, append=…, na=…)
• with(…, expr=…)
• pfd(file=…)
• help()

Operators/Symbols

<-	assign values on the right to the variable on the left
=	same, as used for input arguments in functions
==	is equal to
<	less than
>	greater than
<=	less or equal to
>=	greater than of equal to
()	use to specify arguments for functions or conditions for control structures
	use as mathematical operator to prioritize code to run: 2+3*5 = 17, (2+3)*5 = 25
[]	use to specify indices of variables. In variables with two dimensions (matrix/data.frame) row and column indices are separated by a comma: [row_index, column_index]
{}	use in control structures to specify the code run by the control structure
$	use to specify a variable (column) in a data frame by name

Control structures

if (condition == TRUE) {
   #do this
} else {
   #do that
}

for (i in vector) {
   #do this for length(vector) times, with the value of vector[loop_iteration] stored in i
}

while (condition == TRUE){
   #do this until condition == FALSE
}

function (argument) {
   do something
   return(result)
}

Creating variables

• c()
• paste(…, sep=…)
• vector(mode=…, length=…)
• rep(…, each=…) OR rep(..., times=...)
• seq(from=..., to=..., by=...)
• factor(…, levels=…, labels=…)
• array(…, dim=…)
• matrix(…, nrow=…, ncol=…, byrow=….)
• list()
• data.frame()
• rnorm()
• runif()

• as.character()
• as.double()
• as.integer()
• as.logical()
• as.factor()
• as.Date(…, format=…)

Data information

• class()
• typeof()
• is.character()
• is.double()
• is.integer()
• is.logical()
• is.factor()
• is.numeric()

• length()
• dim()
• nrow()
• ncol()
• table()

• head()
• tail()
• names()
• str()
• unique()
• summary()

Data manipulation

• cbind()
• rbind()
• order(…, decreasing=…)
• merge(x=…, y=…, by=…, all=…)
• rowSums()
• colSums()
• sample()

Calculations

• sum(…, na.rm=…)
• mean(…, na.rm=…)
• max(…, na.rm=…)
• min(…, na.rm=…)
• median(…, na.rm=…)
• var(…, na.rm=…)
• sd(…, na.rm=…)
• sqrt()
• log()
• exp()
• abs()
• round()

Plotting

• par(las=…, bg=…, mar=…, oma=…, mfrow=…, mfcol=…, add=…, cex=…)
• plot.new()
• plot.window(xlim=…, ylim=…)
• windows(width=…, height=…) OR quartz(width=…, height=…)
• plot(x=…, y=…, type=…, pch=…., lty=…, lwd=…, col=…, xlab=…, ylab=…, main=…)
• barplot()
• hist()
• boxplot(y~x, data=…)
• points()
• lines()
• abline()
• segments()
• arrows()
• rect()
• polygon()
• text()
• colors()
• title()
• mtext()
• axis()
• box()
• dev.off()
• graphics.off()

Linear Algebra

• %*%
• t()
• diag()