[R] Matrix interesting question!
David Winsemius
dwinsemius at comcast.net
Fri May 28 20:21:11 CEST 2010
On May 28, 2010, at 12:30 PM, UM wrote:
>
> hi,
> I have been trying to do this in R (have implemented it in Excel)
> but I have
> been using a very inefficent way (loops etc.). I have matrix A
> (columns are
> years and ages are rows) and matrix B (columns are birth yrs and
> rows are
> ages)
>
>
> I would like to first turn matrix A into matrix B
>
> catrow <- function(A, rn) c(rep("0", 3-rn), A[rn,],rep("0",
(2+rn)-3) )
> matrix(sapply(1:3, function(x) catrow(A, x)) , ncol=2*ncol(A)-1,
byrow=TRUE)
[,1] [,2] [,3] [,4] [,5]
[1,] "0" "0" "a" "b" "c"
[2,] "0" "d" "e" "f" "0"
[3,] "g" "h" "i" "0" "0"
> And then I would like to convert matrix B back again to the original
> matrix
> A.
Left as an exercise for the reader.
> (I have left out details of steps) but this is the gist of what I
> want to
> do. Can anyone please give any insights?
David Winsemius, MD
West Hartford, CT
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