New package:

David Brahm brahm at
Mon Dec 3 17:25:02 CET 2001

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

Here's the official Description for (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, then read from it and assign to it in
  a manner similar to S-Plus, except that you must run to
  actually commit to disk.

Here's a very abbreviated (Unix) example:"/tmp/mydir")             # Open package:mydir in pos=2
  assign("x1", matrix(1, 1000, 1000), 2)  # Put data there                           # Commit to disk
  detach(2)                               # Detach package:mydir"/tmp/mydir")             # Re-attach it, no resources used
  dim(x1)                                 # x1 is loaded only when needed!
  find("x1")                              # It still lives in package:mydir 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 at> and (by reference) Ray Brownrigg
<Ray.Brownrigg at>, who suggested using delay(); Martin Maechler
<maechler at>, Thomas Lumley <tlumley at>, Brian
D. Ripley <ripley at>, and Peter Dalgaard
<p.dalgaard at>, who helped me with platform independence issues;
and Kurt Hornik <Kurt.Hornik at>, who cleaned it up for CRAN.

I have one concern: 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 at

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