New package: g.data

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From: David Brahm (brahm@alum.mit.edu)
Date: Tue 04 Dec 2001 - 03:25:02 EST


Message-id: <15371.42846.422155.287658@gargle.gargle.HOWL>


A new package "g.data" is available on CRAN, to create and maintain databases
that work more like the S-Plus model.

Here's the official Description for g.data (v1.2):
  Create and maintain delayed-data packages (DDP's). Data stored in
  a DDP are available on demand, but do not take up memory until requested.
  You attach a DDP with g.data.attach(), then read from it and assign to it in
  a manner similar to S-Plus, except that you must run g.data.save() to
  actually commit to disk.

Here's a very abbreviated (Unix) example:
  g.data.attach("/tmp/mydir") # Open package:mydir in pos=2
  assign("x1", matrix(1, 1000, 1000), 2) # Put data there
  g.data.save() # Commit to disk
  detach(2) # Detach package:mydir
  g.data.attach("/tmp/mydir") # Re-attach it, no resources used
  dim(x1) # x1 is loaded only when needed!
  find("x1") # It still lives in package:mydir

g.data is the end result of my post "Reading and writing to S-like databases",
sent to R-help on Sep 28, 2001. Thanks to all who responded, especially
Dr. Agustin Lobo <alobo@ija.csic.es> and (by reference) Ray Brownrigg
<Ray.Brownrigg@mcs.vuw.ac.nz>, who suggested using delay(); Martin Maechler
<maechler@stat.math.ethz.ch>, Thomas Lumley <tlumley@u.washington.edu>, Brian
D. Ripley <ripley@stats.ox.ac.uk>, and Peter Dalgaard
<p.dalgaard@biostat.ku.dk>, who helped me with platform independence issues;
and Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at>, who cleaned it up for CRAN.

I have one concern: g.data relies heavily on delay(), whose documentation says:
  This is an experimental feature and its addition is purely for
  evaluation purposes.
Is there any plan to deprecate delay()?

Feedback is welcome!

-- 
                              -- David Brahm (brahm@alum.mit.edu)

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