R help - Nov 2006 - dumping/loading objects with 'tsp' attribute

Dear all,
I'm indirectly faced with the fact that setting the 'tsp' attribute
of
an object modifies its class definition:
> class( structure(1:2, tsp=c(1,2,1),
class=c("myts","ts")) )
[1] "ts"   "myts"

In general, this is of really little (ok, I admit: totally no)
interest for me because 'myts' class is added just after assigning the
'tsp' attribute (by calling ts).
However, this behaviour gives me troubles when re-loading a previously
deparsed object, so that:
> x <- ts(1:2)
> class(x) <- c("myts", class(x))
> dput( x , "temp.dat")
> class(dget("temp.dat"))
[1] "ts"   "myts"
> unlink("temp.dat")
In other words, my real problem should be restated as: how to safely
dump (and then load) an object which has a (perhaps valid) "tsp"
attribute?
More generally: can someone suggest me a safer way to dump/restoring R objects?

Tnx all,
Antonio.
-- 
Antonio, Fabio Di Narzo
Ph.D. student at
Department of Statistical Sciences
University of Bologna, Italy

On Thu, 23 Nov 2006, Antonio, Fabio Di Narzo wrote:
> Dear all,
> I'm indirectly faced with the fact that setting the 'tsp'
attribute of
> an object modifies its class definition:
>> class( structure(1:2, tsp=c(1,2,1),
class=c("myts","ts")) )
> [1] "ts"   "myts"
>
> In general, this is of really little (ok, I admit: totally no)
> interest for me because 'myts' class is added just after assigning
the
> 'tsp' attribute (by calling ts).
> However, this behaviour gives me troubles when re-loading a previously
> deparsed object, so that:
>> x <- ts(1:2)
>> class(x) <- c("myts", class(x))
>> dput( x , "temp.dat")
>> class(dget("temp.dat"))
> [1] "ts"   "myts"
>> unlink("temp.dat")
>
> In other words, my real problem should be restated as: how to safely
> dump (and then load) an object which has a (perhaps valid) "tsp"
> attribute?
> More generally: can someone suggest me a safer way to dump/restoring R
objects?
save/load.

?dput comes with copious warnings about the problems of doing what you are 
attempting, so I wonder why you are surprised.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595