one approach is:
a <- matrix(1:20,ncol=4); colnames(a) <- c("a","b","c","d")
b <- matrix(1:20,ncol=4); colnames(b) <- c("b","c","d", "e")
cc <- matrix(1:10,ncol=2); colnames(cc) <- c("e","f")
f <- function (...) {
mat.lis <- list(...)
unq.cnams <- unique(unlist(lapply(mat.lis, colnames)))
out <- matrix(0, nrow(mat.lis[[1]]), length(unq.cnams),
dimnames = list(NULL, unq.cnams))
for (i in seq_along(mat.lis)) {
mm <- mat.lis[[i]]
out[, colnames(mm)] <- out[, colnames(mm)] + mm
}
out
}
f(a, b)
f(a, cc)
f(a, b, cc)
I hope it helps.
Best,
Dimitris
murali.me...@fortisinvestments.com wrote:
folks,
if i have three matrices, a, b, cc with some colnames in common, and i
want to create a matrix which consists of the common columns added up,
and the other columns tacked on, what's a good way to do it? i've got
the following roundabout code for two matrices, but if the number of
matrices increases, then i'm a bit stymied.
a <- matrix(1:20,ncol=4); colnames(a) <- c("a","b","c","d") b <-
matrix(1:20,ncol=4); colnames(b) <- c("b","c","d", "e")
cbind(a[,!(colnames(a) %in% colnames(b)), drop = FALSE],
a[,intersect(colnames(a),colnames(b))] +
b[,intersect(colnames(a),colnames(b)), drop = FALSE],
b[,!(colnames(b) %in% colnames(a)), drop = FALSE])
a b c d e
[1,] 1 7 17 27 16
[2,] 2 9 19 29 17
[3,] 3 11 21 31 18
[4,] 4 13 23 33 19
[5,] 5 15 25 35 20
now, what if i had a matrix cc? i want to perform the above operation on
all three matrices a, b, cc.
cc <- matrix(1:10,ncol=2); colnames(cc) <- c("e","f")
i need to end up with:
a b c d e f
[1,] 1 7 17 27 17 6
[2,] 2 9 19 29 19 7
[3,] 3 11 21 31 21 8
[4,] 4 13 23 33 23 9
[5,] 5 15 25 35 25 10
and, in general, with multiple matrices with intersecting colnames?
thanks,
murali
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--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
