R help - Jan 2005 - [basic ?] Merging result of by processing with a data frame

Dear All,

I would like to merge a data frame such as:
> basetab
   subject dose  cmax
1     1031   50  21.8
....

with the result of a by processing such as:
> tmax<-by(pkga,subject,f.tmax)
> tmax
subject: 1031
[1] 6
--------------------------------------------------

f.tmax being a function written by H. Nguyen (in applied statistics in
the pharmaceutical industry). pkga is a data frame with subject conc
time variates.

The aim is to have a single data frame with subject dose cmax tmax etc
(AUCs) ... so that I can do summary stats and plots by dose.


I have tried unlist without success.

Thanks for any help.

Kind regards, Jean-Louis