1 Preamble
The goal of the present document is to give a starting point for people newly
interested in R. I chose to emphasize on the understanding of how R works,
with the aim of a beginner, rather than expert, use. Given that the possibilities
offered by R are vast, it is useful to a beginner to get some notions and
concepts in order to progress easily. I tried to simplify the explanations as
much as I could to make them understandable by all, while giving useful
details, sometimes with tables.
R is a system for statistical analyses and graphics created by Ross Ihaka
and Robert Gentleman
1
. R is both a software and a language considered as a
dialect of the S language created by the AT&T Bell Laboratories. S is available
as the software S-PLUS commercialized by Insightful
2
. There are important
differences in the designs of R and of S: those who want to know more on this
point can read the paper by Ihaka & Gentleman (1996) or the R-FAQ
3
, a copy
of which is also distributed with R.
R is freely distributed under the terms of the GNU General Public Licence
4
;
its development and distribution are carried out by several statisticians known
as the R Development Core Team.
R is available in several forms: the sources (written mainly in C and
some routines in Fortran), essentially for Unix and Linux machines, or some
pre-compiled binaries for Windows, Linux, and Macintosh. The files needed
to install R, either from the sources or from the pre-compiled binaries, are
distributed from the internet site of the Comprehensive R Archive Network
(CRAN)
5
where the instructions for the installation are also available. Re-
garding the distributions of Linux (Debian, . . . ), the binaries are generally
available for the most recent versions; look at the CRAN site if necessary.
R has many functions for statistical analyses and graphics; the latter are
visualized immediately in their own window and can be saved in various for-
mats (jpg, png, bmp, ps, pdf, emf, pictex, xfig; the available formats may
depend on the operating system). The results from a statistical analysis are
displayed on the screen, some intermediate results (P-values, regression coef-
ficients, residuals, . . . ) can be saved, written in a file, or used in subsequent
analyses.
The R language allows the user, for instance, to program loops to suc-
cessively analyse several data sets. It is also possible to combine in a single
program different statistical functions to perform more complex analyses. The
1
Ihaka R. & Gentleman R. 1996. R: a language for data analysis and graphics. Journal
of Computational and Graphical Statistics 5: 299–314.
2
See
http://www.insightful.com/products/splus/default.asp for more information
3
http://cran.r-project.org/doc/FAQ/R-FAQ.html
4
For more information:
http://www.gnu.org/
5
http://cran.r-project.org/
1
