Rui et.al.: But apply will not work if the data frame has columns of different classes/types, as appears to be the case here. Viz, from ?apply:
"If X is not an array but an object of a class with a non-null dim<http://127.0.0.1:12824/help/library/base/help/dim> value (such as a data frame),apply attempts to coerce it to an array via as.matrix if it is two-dimensional (e.g., a data frame) or via as.array." Simply looping by rows (via for() ) appears to be the simplest and probably fastest solution. There are other ways via tapply() and friends, but these are also essentially loops and are likely to incur some additional overhead. All assuming I understand what the OP has requested, of course. Cheers, Bert On Sun, Sep 1, 2013 at 7:31 AM, Rui Barradas <ruipbarra...@sapo.pt> wrote: > Hello, > > Maybe you need apply, not lapply. It seems you want to apply() a function > to the first dimension of your data.frame, something like > > apply(dat, 1, fun) #apply by rows > > > Hope this helps, > > Rui Barradas > > Em 01-09-2013 15:00, Ignacio Martinez escreveu: > >> I have a Data Frame that contains, between other things, the following >> fields: userX, Time1, Time2, Time3. The number of observations is 2000. >> >> I have a function that has as inputs userX, Time1, Time2, Time3 and return >> a data frame with 1 observation and 19 variables. >> >> I want to apply that function to all the observations of the first data >> frame to make a new data frame with 2000 observations and 19 variables. >> >> I thought about using lapply, but if I understand correctly, it only takes >> one variable. >> >> Can somebody point me in the right direction? >> >> Thanks! >> >> [[alternative HTML version deleted]] >> >> ______________________________**________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help> >> PLEASE do read the posting guide http://www.R-project.org/** >> posting-guide.html <http://www.R-project.org/posting-guide.html> >> and provide commented, minimal, self-contained, reproducible code. >> >> > ______________________________**________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help> > PLEASE do read the posting guide http://www.R-project.org/** > posting-guide.html <http://www.R-project.org/posting-guide.html> > and provide commented, minimal, self-contained, reproducible code. > -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
