extracting submatrix from a bigger one
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$ID,I) See ?by, ?tapply, and ?split -- Bert
On Mon, Jun 24, 2013 at 9:24 AM, Rui Barradas <ruipbarradas at sapo.pt> wrote:
Hello, Try the following. result <- lapply(unique(dataset$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
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