From: David Brahm (email@example.com)
Date: Tue 04 Dec 2001 - 03:25:02 EST
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 <firstname.lastname@example.org> and (by reference) Ray Brownrigg
<Ray.Brownrigg@mcs.vuw.ac.nz>, who suggested using delay(); Martin Maechler
<email@example.com>, Thomas Lumley <firstname.lastname@example.org>, Brian
D. Ripley <email@example.com>, and Peter Dalgaard
<firstname.lastname@example.org>, 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
Is there any plan to deprecate delay()?
Feedback is welcome!
-- -- David Brahm (email@example.com)
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