[R] "problem" with delay()

[Ray Brownrigg]

I asked:
> > I have been using delay()  quite successfully to 'load on reference'
> > some large data files (earthquake catalogues).  One minor difficulty I
> > have not been able to overcome is that upon first reference, the data
> > set is loaded into memory as expected, but also remains as a permanent
> > object in the user's environment, instead of appearing to be only in
> > the library from which it was loaded. 
> 
Thomas Lumley <thomas at biostat.washington.edu> replied:
> Your problem is that data() does load the object into the global
> environment. To put data in another environment you need to use load(),
> source(), read.table() &c, explicitly.
> 
> :
> 
> Alternatively, if your data are in the R save() format and you are using
> 1.1.0 or newer you can delay an attach command
> 
> test.x<-delay({attach("data.rda")})
> 
> or if the file is in the data subdirectory of "mypackage"
> 
> test.x<-delay({attach(system.file("data","data.rda",pkg="mypackage"))})
> 
> This loads the file into a new environment in the search path, so it won't
> be saved on exit.
> 
[Almost] exactly what I wanted.  The above does not actually provide the
value on first reference, so the minor modification to:
test.x<-delay({attach(system.file("data","data.rda",pkg="mypackage")); test.x})
is what works for me.

Thank you.

Regards,
Ray Brownrigg
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