Using the lazy data mechanism

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Using the lazy data mechanism

Fox, John
Dear list members,

I'm trying to use the lazy data mechanism with the car package, so far
without success. The data sets are in the source package's data subdirectory
in the form of compressed .rda files, and I added the directive LazyData:
yes to the package's DESCRIPTION file.

I suspect that the problem is that the package has no namespace, but I've
been unable to find a reference in the Writing R Extensions manual (nor
elsewhere) that suggests that this is necessary. Is there a place that I've
missed that describes the lazy data mechanism?

My system info:

----- snip -----

Version:
 platform = i386-pc-mingw32
 arch = i386
 os = mingw32
 system = i386, mingw32
 status =
 major = 2
 minor = 2.1
 year = 2005
 month = 12
 day = 20
 svn rev = 36812
 language = R

Windows XP Professional (build 2600) Service Pack 2.0

Locale:
LC_COLLATE=English_United States.1252;LC_CTYPE=English_United
States.1252;LC_MONETARY=English_United
States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252

Search Path:
 .GlobalEnv, package:MASS, package:car, package:methods, package:stats,
package:graphics, package:grDevices, package:utils, package:datasets,
package:svIO, package:R2HTML, package:svMisc, package:svSocket,
package:svIDE, package:tcltk, Autoloads, package:base

----- snip -----

Thanks,
 John

--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
905-525-9140x23604
http://socserv.mcmaster.ca/jfox

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Re: Using the lazy data mechanism

Brian Ripley
John,

There are lots of examples without a namespace on CRAN.  The first in the
alphabet (in the C locale) is DAAG.  Another example (but handled
specially) is package 'datasets'.

Taking the version on CRAN (car_1.0-18) and adding

LazyData: yes
LazyLoad: yes

worked for me (and you don't actually need the second, as it works whether
or not the R code is lazy-loaded).

Perhaps you can let me know offline what the problems are?

Brian

On Sat, 4 Feb 2006, John Fox wrote:

> Dear list members,
>
> I'm trying to use the lazy data mechanism with the car package, so far
> without success. The data sets are in the source package's data subdirectory
> in the form of compressed .rda files, and I added the directive LazyData:
> yes to the package's DESCRIPTION file.
>
> I suspect that the problem is that the package has no namespace, but I've
> been unable to find a reference in the Writing R Extensions manual (nor
> elsewhere) that suggests that this is necessary. Is there a place that I've
> missed that describes the lazy data mechanism?

There's are article in R-news, but that describes the mechanism per se.
How to use it is in `Writing R Extensions'.

[...]

--
Brian D. Ripley,                  [hidden email]
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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