[R] appending objects to a file created by save()

David Whiting david.whiting at ncl.ac.uk
Fri Mar 10 10:49:52 CET 2006

On Fri, 2006-03-10 at 03:46 -0500, Rajarshi Guha wrote:
> Hi,
>   I've been slowly transitioning to saving sets of objects for a project
> using save() rather than cluttering my workspace and then doing
> save.image()
> However, sometimes after I have done say:
> save(x,y,z, file='work.Rda')
> and I reload it a little later and  I see that I also want to save
> object p. Currently I need to do:
> save(x,y,z,p, file='work.Rda')
> Is there any way to instruct save to append an object to a previously
> created binary data file?

I use this approach. One potential problem with this approach is that if
you have large saved objects you could get into problems because you
need to load them before saving them. 

## Function to append an object to an R data file.
append.Rda <- function(x, file) {
  old.objects <- load(file, new.env())
  save(list = c(old.objects, deparse(substitute(x))), file = file)

## Example:
x <- 1:10
y <- letters[1:10]
save(list = c("x", "y"), file = "temp.Rda")
z <- "fred"
append.Rda(z, "temp.Rda")


> Thanks,
> -------------------------------------------------------------------
> Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
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