[R] Save workspace with ff objects

[Jens Oehlschlägel]

> My script generates a mixture of normal and ff objects. 
> Very often I would like to save the workspace for 
> each parameter setting, so that I can get back to it later on.
> Is there an easy way to do this, 
> instead of needing to save individual ff objects separately? 

With one save() you can store as many ff objects as you like. 
However, this does not save the ff files to a different location.

> I've tried the naive way of just saving the workspace, only to find that ff objects are empty.

When loading the ff objects, the ff files need to be in their original locations.
You need to make sure that you do not overwrite those 
and they survive finalizer and tempdir remove at rm(ff) or q() time.
Do read the ff help on parameters 'filename', 'pattern', 'finalizer', 'finonexit'.

The next version of ff will have ffsave() 
which will store a mixture of normal and ff objects 
*and* all ff-files into a ffarchive, i.e. two files 
<ffarchive>.RData and <ffarchive>.ffData 
from which you can restore all or a selection of 
ff objects / files using the ffload() command.

Regards
Jens Oehlschlägel