[R] New project: littler for GNU R

[Jeffrey Horner]

What ?
======

   littler - Provides hash-bang (#!) capability for R (www.r-project.org)


Why ?
=====

   GNU R, a language and environment for statistical computing and
   graphics, provides a wonderful system for 'programming with data'
   as well as interactive exploratory analysis, often involving graphs.

   Sometimes, however, simple scripts are desired. While GNU R can
   be used in batch mode, and while so-called 'here' documents can be
   crafted, a long-standing need for a scripting front-end has often
   been expressed by the R Community.

   littler (pronounced 'little R' and written 'r') aims to fill
   this need.

   It can be used directly on the command-line just like, say, bc(1):


         $ echo 'cat(pi^2,"\n")' | r
         9.869604

   Equivalently, commands that are to be evaluated can be given on
   the command-line

         $ r -e 'cat(pi^2, "\n")'
         9.869604

   But unlike bc(1), GNU R has a vast number of statistical
   functions. For example, we can quickly compute a summary() and show
   a stem-and-leaf plot for file sizes in a given directory via

         $ ls -l /boot | awk '!/^total/ {print $5}' | \
              r -e 'fsizes <- as.integer(readLines());
                 print(summary(fsizes)); stem(fsizes)'
            Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
              13     512  110100  486900  768400 4735000
         Loading required package: grDevices

           The decimal point is 6 digit(s) to the right of the |

           0 | 00000000000000000011112223
           0 | 5557778899
           1 | 112233
           1 | 5
           2 |
           2 |
           3 |
           3 |
           4 |
           4 | 7


   And, last but not least, this (somewhat unwieldy) expression can
   be stored in a helper script:

         $ cat examples/fsizes.r
         #!/usr/bin/env r

         fsizes <- as.integer(readLines())
         print(summary(fsizes))
         stem(fsizes)

   (where calling /usr/bin/env is a trick from Python which allows one
   to forget whether r is installed in /usr/bin/r, /usr/local/bin/r,
   ~/bin/r, ...)

   A few examples are provided in the source directories examples/
   and tests/.

Where ?
=======

   littler can either be downloaded from

       http://biostat.mc.vanderbilt.edu/LittleR

   accessed by anonymous SVN:

       $ svn co http://littler.googlecode.com/svn/trunk/ littler

   or (soon !) be gotten from Debian mirrors via

       $ agt-get install littler

   littler is known to build and run on Linux and OS X.


Who ?
=====

   Copyright (C) 2006 Jeffrey Horner and Dirk Eddelbuettel

   littler is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public
   License along with this program; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
   MA  02111-1307  USA

   Comments are welcome, as are are suggestions, bug fixes, or patches.


     - Jeffrey Horner <jeff.horner at vanderbilt.edu>
     - Dirk Eddelbuettel <edd at debian.org>