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 in a beta test state and we are seeking
comments and bug reports.  Please send comments and reports to

    R@stat.auckland.ac.nz

In the case of bugs it would be very helpful to have code which
reliably reproduces the problem.  Some bugs can be very hard to
fix without this.


2. PRESENT STATUS

We have implemented 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.


3. 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.

Our present plan of attack is as follows:

1.  Re-implement parts of the system to make things more modular
    so that data sets can be saved and restored on an individual
    basis and so that we have a real library facility.
    (Mostly done).

2.  Move the user interface to an event driven basis.  This will
    enable users to interact with the system in a much more
    graphical way.  It also raises the possibility that we can
    borrow the graphics technology in LispStat.
    (Design phase).

3.  Add functionality in the form of new functions.
    (Ongoing).

4.  The present documentation is written using our own format into 
    files which can be processed by a combination of sed and m4 into
    a variety of formats (nroff, latex, html).  We should use a real
    SGML description of our format and develop techniques for more
    generally translating into other formats.

Longer-term we are hoping to move to a compiled evironment which
will give substantial performance gains.  A separate compiler
"skunk works" is engaged in this.


4. 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