Here's a way to convert a matrix of vectors like you have into an array: > x <- array(lapply(seq(0,len=6,by=4), "+", c(a=1,b=2,c=3,d=4)), dim=c(2,3), dimnames=list(c("X","Y"),c("e","f","g"))) > x e f g X Numeric,4 Numeric,4 Numeric,4 Y Numeric,4 Numeric,4 Numeric,4 > x[["Y","e"]] a b c d 5 6 7 8 > xa <- array(unlist(x, use.names=F), dim=c(length(x[[1,1]]),dim(x)), dimnames=c(list(names(x[[1,1]])),dimnames(x))) > x["Y","e"] [[1]] a b c d 5 6 7 8
> xa[,"Y","e"] a b c d 5 6 7 8 > Then you can do whatever sums you want over the array. I have not extensively checked the above code, and if I were going to use it, I would do numerous spot checks of elements to make sure all the elements are going to the right places -- it's not too difficult to make mistakes when pulling apart and reassembling arrays like this. (For simpler cases involving lists of vectors or matrices, the abind() function can help.) -- Tony Plate Jessica Gervais wrote: > Hi, > > I need some help > > I have a matrix M(m,n) in which each element is a vector V of lenght 6 > 1 2 3 4 5 6 7 > 1 List,6 List,6 List,6 List,6 List,6 List,6 List,6 > 2 List,6 List,6 List,6 List,6 List,6 List,6 List,6 > 3 List,6 List,6 List,6 List,6 List,6 List,6 List,6 > 4 List,6 List,6 List,6 List,6 List,6 List,6 List,6 > > > i would like to make the sum on the matrix of each element of the > matrix, that is to say > sum(on the matrix)(M[j,][[j]][[1]]) > sum(on the matrix)(M[j,][[j]][[2]]) > ... > sum(on the matrix)(M[j,][[j]][[6]]) > > I don't really know how to do. > I thought it was possible to transform the matrix M into an array A of > dimension (m,n,6), and then use the command sum(colsums(A[,,1]), which > seems to be possible and quite fast. > ...but I don't know how to convert a matrix of vector into an array.... > > As anyone any little idea about that ? > > Thanks by advance > > Jessica > > ______________________________________________ > R-help@stat.math.ethz.ch 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@stat.math.ethz.ch 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.