Hi: The : operator is meant for numeric sequences; see ?':'
On Tue, Jan 19, 2010 at 7:57 PM, rusers.sh <rusers...@gmail.com> wrote: > Hi, > I know we can use 1:10 to represent the 1,2,3,...,10 numbers, but the > following conditions are except. > Anybody knows how to represent the following two cases with similar usage > of ":" or others? Usually, i will get several hundred names for them, such > as a1,a2,... or f[[1]],f[[2]],... > #Example data > a1<-array(1:12,c(2,3,2)); a2<-array(2,c(2,3,2)); a3<-array(0,c(2,3,2)) > a1[1,2,1]:a3[1,2,1] > [1] 3 2 1 0 > #the correct result should be 3,2,0 > I tried this: > a <- list(a1, a2, a3) > unlist(lapply(a, '[', 1, 2, 1)) [1] 3 2 0 If you're trying to get the same element out of a bunch of arrays, this might be one way to go. You might also want to investigate the iapply function in the iterators package, since it manipulates indices in 3D arrays rather easily. HTH, Dennis So the method of using "a1[i,j,k]:a3[i,j,k]" to represent > "c(a1[i,j,k],a2[i,j,k],a3[i,j,k])" is not correct? > ##For lists with matrices as its elements > f<-list() > f[[1]]<-a1;f[[2]]<-a2;f[[3]]<-a3 > f[[1]][1,2,1]:f[[3]][1,2,1] > [1] 3 2 1 0 > #the correct result should be 3,2,0 > So the method of using "f[[1]][i,j,k]:f[[3]][i,j,k]" to represent > "f[[1]][i,j,k],f[[2]][i,j,k],f[[3]][i,j,k])" is not correct? > I noticed that the above two methods have got the same results, although > not correct. So i guess i have made the same errors in them. Is there some > method to represent them concisely? > Any ideas about them? > Thanks a lot. > > > -- > ----------------- > Jane Chang > Queen's > > [[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.
