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

[Duncan Murdoch]

On 13/01/2019 3:38 a.m., 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
> 

Does that every happen when ls() returns character(0)?  It seems likely 
that you have copies of them in the global workspace, and the message is 
correct.

In the earlier situation (ls() *does* return character(0), but x is 
still found), you can find where it was found using

getAnywhere("x")

For example,

 > x <- 2
 > getAnywhere("x")
A single object matching ‘x’ was found
It was found in the following places
   .GlobalEnv
with value

[1] 2

Duncan Murdoch