The R Project SVN R

            THE BASIC R README

       (See "RESOURCES" for additional resources)



1. INTRODUCTION

This directory contains the Unix source code tree for R, which is
a language which is not entirely unlike the S language developed
at AT&T Bell Laboratories by Rick Becker, John Chambers and Allan
Wilks.  Indeed in the (present) absence of an R manual, you can
(mostly) get along by using the S manual.

R is free software distributed under a GNU-style copyleft.

Currently the software is undergoing active development.  Discussion
of the development process is carried out on the "r-devel" mailing
list.  See the file RESOURCES for details on how to subscribe to
this list.


2. HISTORY

R was initially written by Robert Gentleman and Ross Ihaka of the
Statistics Department of the University of Auckland.  In addition,
a large group of individuals has contributed to R by sending code
and bug reports. 

Since mid-1997 there has been a core group who can modify the R
source code CVS archive.  The group currently consists of

    Peter Dalgaard, Robert Gentleman, Kurt Hornik, Ross Ihaka,
    Friedrich Leisch, Thomas Lumley, Martin Maechler,
    Paul Murrell, Heiner Schwarte, and Luke Tierney.

As noted above, discussions of the development process take
place in the r-devel mailing list.


3. PRESENT STATUS

The present version implements most of the functionality in the
first S book (the "Blue Book") and many of the applications.  In
addition, we have implemented a certain amount of functionality
from the second S book (the "White Book").  In particular we have
a functioning versions of "lm" and "glm" and their associated
"summary" and "anova" methods (it would be nice to have "drop1",
"add1" and "step", but there hasn't been time to complete these
yet).

What we have in the way of manual is in the directory in an
"output independent" form which can be used to create versions
for HTML, LaTeX, troff etc.


4. GOALS

Our aim at the start of this project was to demonstrate that it was
possible to produce an S-like environment which did not suffer from
the memory-demands and performance problems which S has.  It is only
recently that we have started trying to turn R into a "real" system.
In the short term we hope to create a small portable free system
which will provide most of the functionality of S and perhaps some
extensions.

Future versions will see R converted to GNU coding standards.


5. SOME DIFFERENCES BETWEEN R AND S

1. In R, "factor" and "ordered factor" are primitive vector types.
   This means in particular that they can be shaped as arrays.

2. In R a list is a Lisp-style list composed of dotted pairs, rather
   than a vector of generic elements as in S.  This means that list
   subscripting can be rather inefficient.  However, lists are rarely
   large and so we have not (yet) bothered to implement a matching
   "generic vector" type, even though this could be quite useful.

Robert Gentleman + Ross Ihaka + The R core.