?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
Double Roop
3 messages · Peter Maclean, Sarah Goslee, David Winsemius
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 at 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 at 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
On Jun 30, 2015, at 6:04 AM, Peter Maclean via R-help 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]]
If you don't want folks here to think you have difficulty with the English language in the posting guide or with managing computer applications, you will set your mail-client to plain-text for communications to r-help. Notice that your code was a bit mangled by the HTML format. This is sometimes much more of a problem than it was in this instance. You've been posting since 2011 so really have no excuse for continuing to flout the mailing list norms:
page <- paste( rep(a, length(b) ), rep(b, each =length(a) ) ) page
[1] "A-AA 1" "B-BB 1" "C-CC 1" "A-AA 2" "B-BB 2" "C-CC 2" "A-AA 3" [8] "B-BB 3" "C-CC 3" "A-AA 4" "B-BB 4" "C-CC 4" "A-AA 5" "B-BB 5" [15] "C-CC 5"
______________________________________________ R-help at 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.
David Winsemius Alameda, CA, USA