Hi Peter, page is indexed by [i], so for each iteration of j you're rewriting previous results.
You can fix that very simply, with: a <- c("A-AA", "B-BB", "C-CC") b <- seq(1, 5) pre <- NULL post <- NULL page <- NULL pageno <- 1 for(j in 1:length(a)) { for(i in 1:length(b)){ pre[j] <- strsplit(a[j],"-")[[1]][1] post[j] <- strsplit(a[j],"-")[[1]][2] page[pageno] <- paste0(pre[j], b[i],post[j]) pageno <- pageno + 1 }} But try instead: a <- c("A-AA", "B-BB", "C-CC") b <- seq(1, 5) page <- expand.grid(b, a) apply(page, 1, function(x)sub("-", x[1], x[2])) Sarah PS Please don't post in HTML; I had to unmangle your code before working with it. On Tue, Jun 30, 2015 at 9:04 AM, Peter Maclean via R-help <r-help@r-project.org> wrote: > Hi EverybodyI am trying to make an object with length(a) * length(b) > element using a double loop. But I am getting the last part only. A simple > script is > a <- c("A-AA", "B-BB", "C-CC") > b <- seq(1, 5) > pre <- NULL > post <- NULL > page <- NULLfor(j in 1:length(a)) { > for(i in 1:length(b)){ > pre[j] <- strsplit(a[j],"-")[[1]][1] > post[j] <- strsplit(a[j],"-")[[1]][2] > page[i] <- paste0(pre[j], b[i],post[j]) > }}Peter Maclean > Department of Economics > UDSM > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. -- Sarah Goslee http://www.functionaldiversity.org ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.