First of all, is your data structure a matrix or a data frame? They are different!
Assuming the latter, a shorter version of Rui's answer that avoids unique() and automatically takes care of names is: result <- by(dataset, dataset$ID,I) See ?by, ?tapply, and ?split -- Bert On Mon, Jun 24, 2013 at 9:24 AM, Rui Barradas <ruipbarra...@sapo.pt> wrote: > Hello, > > Try the following. > > > result <- lapply(unique(dataset$ID), function(uid) dataset[dataset$ID == > uid, ]) > names(result) <- unique(dataset$ID) > > > Hope this helps, > > Rui Barradas > > Em 24-06-2013 15:36, matteo escreveu: >> >> Hi guys, >> I'm a newby, so sorry for the easy question. >> >> I have a matrix (459x28) in which a large number of observations are >> repeated (same placed sampled in different times). >> One of the columns is refers to the ID of the place of sampling. >> What I would like is to extract subset matrix for every point of sampling. >> >> I can do it manually, e.g. x1<-data.frame(dataset[dataset$ID=="x1",]) >> but is it possible to write a script and let do it to R? >> So i got n submatrix of the n ID found in the original columns. >> >> Cheers >> >> Matteo >> >> ______________________________________________ >> 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. > > > ______________________________________________ > 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. -- 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 ______________________________________________ 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.
