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.
______________________________________________ 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.