As per the R Language definition (Version 4.3.1 (2023-06-16) DRAFT) : R is a system for statistical computation and graphics. It provides, among other things, a pro- gramming language, high level graphics, interfaces to other languages and debugging facilities.

Why R??

1. Free, Open Source and Available on every major platform
2. Massive Set of packages for statistical modelling, machine learning, visualisation and importing and manipulating data
3. Cutting edge tools
4. Deep-seated language support for data analysis
5. A vibrant community
6. Powerful tools for communicating your results
7. A strong foundation on functional programming
8. Existence of IDE (www.rstudio.com/ide/)
9. Powerful meta programming facilities
10. Designed to connect to high-performance programming languages like C, Fortran and C++

Cons of R

1. Codes written in haste
2. R Community more focused on results rather that processes
3. Code mostly written to reduce the amount of typing and hence too hard to understand
4. Inconsistency across contributed packages. (almost 30 years of evolution)
5. R is a profligate user of memory

Overview of the R-System

• The R system for statistical computing consists of two major parts: the base system and a collection of user contributed add-on packages.The R language is implemented in the base system. Implementations of statistical and graphical procedures are separated from the base system and are organised in the form of packages.Both the base system and packages are distributed via the Comprehensive R Archive Network(CRAN) accessible under http://CRAN.R-project.orgThe base system is available in source form and in precompiled form for various Unixsystems, Windows plqtforms and Mac OS X. For the data analyst, it is sufficient to download the precompiled binary distribution and install it locally. Windows users can follow the link: http://CRAN.R-project.org/bin/windows/base/release.html

The base distribution already comes with some high-priority add-on packages namely:

mcgv	KernSmooth	MASS	base
boot	class	cluster	codetools
datasets	foreign	grDevices	graphics
grid	lattice	methods	nlme
nnet	rcompgen	rpart	spatial
splines	stats	stats4	survival
tcltk	tools	utils

Help and Documentation

Roughly, three different forms of documentation for the R system for statistical computing may be distinguished:

1. online help that comes with the base distribution or packages, 
2. electronic manuals and
3. publications work in the form of books etc

More extensive documentation is available electronically from the collection of manuals at http://CRAN.R-project.org/manuals.html

Some of the electronic manuals available are:

• An Introduction to R: A more formal introduction to data analysis with R .
• R Data Import/Export: A very useful description of how to read and write various external data formats.
• R Installation and Administration: Hints for installing R on special platforms.
• Writing R Extensions: The authoritative source on how to write R programs and packages.

Operators in R

Arithmetic Operators

Operators	Description
+	Add
–	Substract
*	Multiply
/	Divide
^	Exponentiation
%%	modulo (remainder)
%/%	quotient

Relational Operators

<

>

<=

>=

OTHER Operators

Operator	Description
:: , :::	access variables in a namespace
$ , @	component/ slot extraction
[ , [[	indexing
:	Sequence operator
!	negation
& , &&	and
| , ||	or
~	as in formulae
-> , ->>	rightwards assignment
<- , <<-	assignment( right to left)
=	assignment(right to left)
?	help

Constants in R

Constant Name	Description
LETTERS	the 26 upper-case letters of the Roman alphabets
letters	the 26 lower-case letters of the Roman alphabets
month.abb	the three-letter abbreviation for the English month names
month.name	the English names for the months of the year
pi	the ratio of the circumference of a circle to its diameter

Numeric Constants in R

Name	Description	typeof()
Inf	Infinity	double
NaN	Not a Number	double
NA_real_	Not Available/ Missing Real	double
NA_integer	Not Available/ Missing Integer	integer

• In R numeric constants start with a digit or period and are either a decimal or hexadecimal constant optionally followed by L.Hexadecimal constants start with 0x or 0X followed by a nonemply sequence from 0-9 a-f A-F, which is interpreted as a hexadecimal number optionally followed by a binary exponent. A binary exponent consists of a P or p foowed by an optional plus or minus sign followed by a non-empty sequence of (decimal) digits, and indicates multipication by a power of two.Decimal constants consist of a nonempty sequence of digits possibly containing a period(decimal point), optionally followed by a decimal exponent. A decimal exponent consists of an E or e followed by an optional plus or minus sign followed by a non-empty sequence of digits, and indicates multipication by a power of ten.A constant followed by i is regarded as an imaginary complex number.A numeric constant immediately followed by L is regarded as an integer number when possible.Only the ASCII digits 0-9 are recognized as digits, even in languages which have other other representations of digits. The ‘decimal separator’ is always a period and never a comma.A leading plus or minus is not regarded by the parser as part of a numeric constant by as a unary operator applied to the constant.

Simple Mathematical Functions in R

Function	Description
abs(x)	absolute value
sign(x)	Sign of elements (1,0,-1)
sqrt(x)	square root
floor(x)	largest integer
ceiling(x)	smallest integer
exp(x)	exponential
expm1(x)	e(x) – 1
log2(x)	log with base 2
log10(x)	log with base 10
log1p(x)	log(1+x)
cos(x)	cosine
sin(x)	sine
tan(x)	tangent
acos(x)	arc cosine
asin(x)	arc sine
atan(x)	arc tangent
cosh(x)	hyperbolic cosine
sinh(x)	hyperbolic sine
tanh(x)	hyperbolic tangent
acosh(x)	arc hyperbolic cosine
asinh(x)	arc hyperbolic sine
atanh(x)	arc hyperbolic tangent
cospi(x)	cos(pi*x)
sinpi(x)	cos(pi*x)
tanpi(x)	tan(pi*x)
gamma(x)	gamma function
lgamma(x)	natural log of gamma function
digamma(x)	first derivative of gamma
trigamma(x)	second derivative of gamma
cumsum(x)	cumulative sums
cumprod(x)	cumulative products
cummax(x)	cumulative maxima
cummin(x)	cumulative minima
Im(x)	Imaginary part
Re(x)	Real part of Complex Number
Arg(x)	Argument part of Complex Number
Conj(x)	Compex conjugate
Mod(x)	Modulus

Some Functions from base-package

Index	Description
.Call	Modern Interfaces to C/C++ code
.Internal	Call an Internal Function
.Primitive	Look Up a Primitive Function
.Library	Search Paths for Packages
capabilities	Report capabilities of this build of R
Arithmetic	Arithmetic Operators
Constants	Built-in Constants
NA	Not Available / Missing Values
NULL	The Null object
Internal Methods	Many R-internal functions are generic and allow methods to be written for.
source	Read R code from a file, a connection or expressions
library	loading/attaching and listing of packages
getwd	Get Working Directory
setwd	Set Working Directory
ls	list all objects
Sys.info
Sys.time	Get current Date and Time
Sys.timezone	Get current TIme Zone
Sys.localeconv	Get details of the numerical and monetary representations in the current locale
Sys.sleep	Suspend execution for a time interval
system.time	CPU time used
system.file	FInd name of R system file
system	Invoke system command
system2	Invoke system command
dyn.load	Foreign Function interface
date	system date and time
proc.time	running time of R
quit	terminate an R session
cat	concatenate and print
typeof	The typeof an object
array	creates array
as.array
is.array
c	Combine values into a vector or list
cbind	combine R objects by columns
rbind	combine R objects by rows
integer	Creates objects of type integer
as.integer
is.integer
numeric	Numeric Vectors
range	range of values
vector	Produces a ‘simple’ vector of the given length and mode
as.vector	A generic, attempts to coerce its argument into a vector of a given mode
is.vector	returns TRUE if the vector is of the specified mode having no attributes other than names
append	vector merging
names	names of an object
labels	Find labels from objects
length	length of an object
lengths	length of list or vector elements
sum	sum of vector elements
cumsum	cumulative sums
cumprod	cumuative products
cummax	cumulative maxima
cummin	cumulative minima
summary	object summaries
attach	attach object to search path
detach	detach object from search path
diff	Lagged Differences
function	function definition
is.function	checks whether argument is a function
lapply	Apply function over a list or vector
data.frame	Data Frame
data.matrix	convert dataframe to a numeric matrix
mat.or.vec	Create matrix or vector
t	transpose of a matrix
subset	subsetting vectors or matrix
max.col	Find maximum position in a matrix
diag	Form diagonal matrix
norm	Calculates the norm of the matrix
lower.tri	lower triangle of a matrix
upper.tri	upper triangle of a matrix
dim	dimensions of an object
dimnames	Dimension names of an object
det	calculate determinant of a matrix
chol	The Cholesky Decomposition
chol2inv	Inverse from QR decomposition
eigen	Spectral Decomposition of a matrix
qr	The qr decompostion of a matrix
qr.X	Reconstruct the Q, R or X matrices from a QR object
colSumscolMeans	column Sums/Means
rowSumsrowMeans	row Sums / Means
crossprod	Matrix cross product
unique	extract unique elements
expression	unevaluated expression
eval	evaluate an expression
unlist	flatten list
which	Which indices are true
which.min	Where is the min() or max() or first TRUE of FALSE
ifelse	conditional element selection
warning	Print warning message
warnings	Print warning messages
write	Write data to a file
tempfile	Create name for temporary file
nchar	counts the number of characters
rank	Returns the sample ranks of the values in a vector Ties
zapsmall	Rounding of numbers
utf8ToInt	converts a lenth-one character string encoded in UTF-8 to an integer vector of Unicode code points
IntToUtf8	converts a numeric vector of Unicode code points either to a single character string or a character vector
cut	convert numeric to factor
table	cross tabulation and table creation
marginSums	compute table margins
toString	convert an R object to a character string
strsplit	split the elements of a character vector
call	Function calls
tapply	apply a function to each cell of a ragged array
jitter	add noise to numbers

Some Functions from utils-package

Index	Description
Rhome	R Home directory
RSiteSearch	Search for keywords or phrases in documentation
help	documentation
help.search	search the help system
help.start	hypertext documentation
nsl	look-up for IP address
install.packages	install packages for repositories or local file
installed.packages	find installed packages
available.packages	list available packages at CRAN like repositories
update.packages	Compare Installed Packages with CRAN-like repositories
remove.packages	remove installed packages
browse.Env	Browse objects in environment
browseURL	Load URL in an HTML browser
head	return the first or last part of an object
object.size	report the size allocated to an object
str	list the structure of an arbitrary R object
ls.str	list objects and their structure
zip	create zip archive
unzip	extract or list zip archives
read.fortran	Read Fixed-Format Data in a Fortran-like Style
read.table	Data input
write.table	Data output
as.roman	get roman numeral
sessionInfo	Get and report version information about R, the OS and attached or loaded packages
SHLIB	Build shared object/DLL for Dynamic loading
download.file	download a file from the Internet
example	Run al the R code from the examples part of R’s online help
maintainer	show Package maintainer

Some Functions from graphics-package

Index	Description
barplot	Barplots
hist	histograms
dotchart	cleaveland’s dot plots
plot	scatter plot
stripchart	1-D scatter plots
smoothScatter	Scatterplots with smootheed densities color representation
plot.xy	basic internal plot function
stem	Stem-and-Leaf Plot
boxplot	Box Plots
boxplot.matrix	draw a boxplot for each column(row) of a matrix
bxp	draw Box plots for summaries
matplot	plot columsn of matrices
cdplot	Conditional Density Plots
coplot	conditioning plots
contour	display contours
filledcontour	level (contour) plots
curve	draw function plots
mosaicplot	Mosaic plots
pie	Pie Charts
spineplot	Spine Plots and Spinograms
stars	Star(Spider/Radar) Plots and segment diagrams
strwidth	plotting dimensions of character strings and math expressions
sunflowerplot	Produce a sunflower scatter plot
symbols	Draw symbols(circles, squares, stars, thermometers, boxpots)
frame	creat / start a new plot frame
layout	specifying complex plot arrangements
par	set or query graphical parameters
grid	add grid to plot
abline	add straight ines to a plot
lines	add connected line segments to a plot
segments	Add line segments to a plot
box	draw a box around a plot
clip	set clipping region
axis	add an axis to a plot
axTicks	compute axis tickmark locations
arrows	add arrows to a plot
legend	add legends to plots
text	add text to a plot
title	plot annotation
mtext	write text into the margins of a plot
image	display a color image