[R] Two R sessions?
maechler at stat.math.ethz.ch
Tue Apr 2 10:48:58 CEST 2002
>>>>> "PaulYP" == Paul Y Peng <ypeng at math.mun.ca> writes:
PaulYP> Hi R users, I am still a relatively new R user
PaulYP> migrated from S+. I wonder in R how do you handle
PaulYP> one difference between R and S+. S+ saves objects as
PaulYP> different files in .Data directory while R saves all
PaulYP> objects in a big file .RData. In S+, I can start two
PaulYP> S+ sessions from the same directory and work
PaulYP> simultaneously as long as new objects in the two
PaulYP> sessions are not in the same names. This is
PaulYP> particularly useful in simulation studies. However,
PaulYP> this method fails for R. I am curious how other R
PaulYP> users handle this thing in R. Naively, I can copy
PaulYP> .Rdata into another directory and then start another
PaulYP> R session there. When the job is done, dump all new
PaulYP> objects in one .Rdata into the other .Rdata. But
PaulYP> maybe someone has a better way to do it.
I never work with .RData at all.
I believe in the virtue of ``reproducible'' research and data
analysis and hence almost exclusively work with "scripts", where
I define functions, and call functions defining other objects.
In most cases, I rerun my scripts which may call other scripts
Only rarely (but always when doing simulations), I *do* save
specific objects explicitely, but then I use different file
names than .RData,
e.g. after some expensive simulations,
I might have
save(list= c("x","K0","Kset","n","nK","B", "vK0", "n.matches", "rr"),
where PROJDIR is a character variable containing the project
Then, to start from these results,
I explicitely do
which will restore the "x", "K0", ... objects but only those.
PaulYP> BTW, why does R save objects in one big file rather
PaulYP> than as different files in a directory as S+ does?
Originally, S and S+ save objects in files ``all the time'' (this
is an oversimplification nowadays; in early versions of S it was true)
whereas R does not save anything in files unless told so.
Saving everything in .RData is only upon (direct or indirect)
user request! Look at
Martin Maechler <maechler at stat.math.ethz.ch> http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum LEO C16 Leonhardstr. 27
ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND
phone: x-41-1-632-3408 fax: ...-1228 <><
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