Dear Rui and Murphy, Thanks for your help. Eliza > Date: Fri, 9 May 2014 22:55:27 +0100 > From: ruipbarra...@sapo.pt > To: eliza_bo...@hotmail.com; r-help@r-project.org > Subject: Re: [R] adding rows > > Hello, > > Try the following. > > sapply(1:(30 - 2), function(i) sum(el[i:(i+2), ])) > > > but with number of rows instead of 30. > > Hope this helps, > > Rui Barradas > > Em 09-05-2014 22:35, eliza botto escreveu: > > Dear useRs, > > I have a matrix, say "el" of 30 rows and 10 columns, as > > el<-matrix(sample(1:300),ncol=10) > > I want to sum up various sets of three rows of each column in the following > > manner > > sum(el[c(1,2,3),]) ##adding row number 1, 2 and 3 of each column > > sum(el[c(2,3,4),])##adding row number 2, 3 and 4 of each column > > sum(el[c(3,4,5),])##adding row number 3, 4 and 5 of each column > > sum(el[c(4,5,6),]) > > sum(el[c(5,6,7),]) > > sum(el[c(6,7,8),]) > > sum(el[c(7,8,9),]) > > sum(el[c(8,9,10),]) > > sum(el[c(9,10,11),]) > > ................ > > ...... > > so on > > .............. > > I know how to do it manually, but since my original matrix has 2000 rows, I > > therefore want to figure out a more conveinient way. > > Thankyou so very much in advance, > > > > Eliza > > [[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. > > [[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.
