[R-pkg-devel] RData files with identical objects in package

[Troels Ring]

Thank you so much! Perhaps it could be mentioned in the official
documentation on writing R extensions - even if - if I can read English -
the 
default is to avoid "lazyData" loading - and "laxyData" loading is in some
opposition to loading using data() - whereas - if we use RStudio, and make
an R documentation file for data, we have it ending with:
\examples{
data(ddd)
## maybe str(ddd) ; plot(ddd) ...
}
\keyword{datasets}

At the same time as "lazyData" is used default in DESCRIPTION ?

1.1.6 Data in packages
The data subdirectory is for data files, either to be made available via
lazy-loading or for loading using data(). (The choice is made by the
'LazyData' field in the DESCRIPTION file: the default is not to do so.) It
should not be used for other data files needed by the package, and the
convention has grown up to use directory inst/extdata for such files.

All best wishes
Troels


-----Oprindelig meddelelse-----
Fra: peter dalgaard <pdalgd using gmail.com> 
Sendt: 13. januar 2019 22:00
Til: Troels Ring <tring using gvdnet.dk>
Cc: Michael Dewey <lists using dewey.myzen.co.uk>; package-develop
<r-package-devel using r-project.org>
Emne: Re: [R-pkg-devel] RData files with identical objects in package

I think it is illegal if you use the lazyload database, because that is
indexed by name and contains every object that would be created by data().
This creates an obvious issue if two objects share a name. 

Once you use the lazyload database, loading the package creates an
environment which is initially full of promises, one for each object.
Evaluating one of these makes the actual object appear in the environment. 

Using data() causes the corresponding promise(s) to be created in the global
environment. IIRC, there is a registry that says which objects are created
by which arguments to data(), but as they are still taken from the lazydata
database, the last one created with a given name still wins.

-ps 

> On 13 Jan 2019, at 14:13 , Troels Ring <tring using gvdnet.dk> wrote:
> 
> Thanks a lot - I'm sure you are right that I could just use different 
> names but I cannot understand why it could cause problem to have two 
> different well formated .RData files in the /data directory both with 
> an "x" - is that really illegal? I cannot see it stated in the 
> official munual - but it is long (wrting r extensions) -BW Troels
> 
> -----Oprindelig meddelelse-----
> Fra: Michael Dewey <lists using dewey.myzen.co.uk>
> Sendt: 13. januar 2019 12:56
> Til: Troels Ring <tring using gvdnet.dk>; package-develop 
> <r-package-devel using r-project.org>
> Emne: Re: [R-pkg-devel] RData files with identical objects in package
> 
> Dear Troels
> 
> Perhaps I misunderstand what you are trying to do but would it be 
> possible to put each x and y into a list or a dataframe with different 
> names and then modify your usgae to pull them from there? Then there 
> would be no danger of users getting the wrong x and y
> 
> Michael
> 
> On 13/01/2019 08:38, Troels Ring wrote:
>> Dear friends - I have a package under creation making heavy 
>> calculations on chemical/clinical data and I plan to include as 
>> "examples" the use of some literature data used in my papers. To 
>> illustrate what then occurs, I made two RData files consisting only 
>> of x and y with different values for x and y like
>> 
>> X <- 100
>> 
>> Y <- 1000
>> 
>> save(x,y,file="first.RData")
>> 
>> and then a new x and y in "second" with x <- 45 and y <- 32
>> 
>> When I put these in a "data" directory of a new package without 
>> further ado in RStudio
>> 
>> Ctrl-shift-L
>> 
>> Ctrl-shift-B
>> 
>> 
>> 
>> .there is a warning
>> 
>> * installing *source* package 'try' ...
>> 
>> ** R
>> 
>> ** data
>> 
>> *** moving datasets to lazyload DB
>> 
>> warning: objects 'x', 'y' are created by more than one data call
>> 
>> ** byte-compile and prepare package for lazy loading
>> 
>> ** help
>> 
>>   converting help for package 'try'
>> 
>> *** installing help indices
>> 
>>     finding HTML links ...    hello
html
>> 
>>  done
>> 
>> 
>> 
>> Now, when I clear the workspace:
>> 
>>> ls()
>> character(0)
>>> devtools::load_all(".")
>> Loading try
>> 
>> Restarting R session...
>> 
>>> library(try)
>>> ls()
>> character(0)
>>> x   #-- so even if workspace Is empty x is still kept
>> [1] 45
>>> data(first) # and "first" is not seen x
>> [1] 45
>> 
>> 
>> 
>> x is still present - and y
>> 
>> 
>> 
>> I have been reading and searching in "Writing R extensions" but so 
>> far didn't find the clue.
>> 
>> Seemingly it is the file with the last name that is assessed - when I 
>> rename first.RData to "xfile.RData" we get 100 and 1000.
>> 
>> Now and then when running ctrl-shift-L and - B we see
>> 
>> 
>> 
>> Attaches package: 'try'
>> 
>> The following objects are masked _by_ '.GlobalEnv':
>> x, y
>> 
>> 
>> 
>> Sorry for these problems -
>> 
>> BW
>> Troels
>> 
>> 
>> 	[[alternative HTML version deleted]]
>> 
>> ______________________________________________
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>> 
> 
> --
> Michael
> http://www.dewey.myzen.co.uk/home.html
> 
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