Try this: mapply('/', l1, l2, SIMPLIFY = FALSE)
and tapply(1:5, lapply(indxLi, as.numeric), sum) On Tue, Mar 15, 2011 at 6:06 PM, Rohit Pandey <rohitpandey...@gmail.com> wrote: > > Hello R community, > > I have two questions about using R. > > The first is about dividing each element of a list with another similar > sized list. So, if the first list has two elements and so does the second, > then the result should also be a list with two elements. > > For example, the inputs are: > > list(matrix(1:6,ncol=2),matrix(1:6,ncol=2))->l1 > l2<-list(1:3,2) > > I want to get a list, l3 with the first element being l1[[1]]/l2[[1]] and > the second one, l1[[2]]/l2[[2]]. > > I had asked a similar question before and the solution using mapply works > well for a list and a vector, but for two lists, it will return an array > (and not a list). > > My second question is about the tapply function. > > tapply(1:5,list(c(1,1,2,2,3),c(1,2,1,1,3)),sum) > will give me: > > 1 2 3 > 1 1 2 NA > 2 7 NA NA > 3 NA NA 5 > The index here is a list: list(c(1,1,2,2,3),c(1,2,1,1,3)). > > However, if I get the same index list through one of the other apply > functions (like by) for example, > indxLi<-by(rbind(c(1,1,2,2,3),c(1,2,1,1,3)),1:2,function(x){return(x)}) > then the tapply no longer works with this list. > tapply(1:5,indxLi,sum) gives me the error: > > Error in sort.list(y) : 'x' must be atomic for 'sort.list' > Have you called 'sort' on a list? > > Is there a way to use the above list in the tapply function? > > Many thanks in advance, > > -- > Thanks, > Rohit > Mob: 91 9819926213 > > [[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. -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O ______________________________________________ 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.