Here's one way:
set.seed(1)
x1 <- lapply(1:5, function(i) rnorm(2))
x2 <- lapply(x1, function(x) outer(x, x))
Reduce("+", x2, 0)
[,1] [,2]
[1,] 1.768406 -1.534413
[2,] -1.534413 3.890200
and another way using the abind package:
library(abind)
dim(abind(along=0, x2))
[1] 5 2 2
colSums(abind(along=0, x2))
[,1] [,2]
[1,] 1.768406 -1.534413
[2,] -1.534413 3.890200
-- Tony Plate
megh wrote:
Hi,
I have created a list object like that :
x = vector("list")
for (i in 1:5) x[[i]] = rnorm(2)
x
Now I want to do two things :
1. for each i, I want to do following matrix calculation : t(x[[i]]) %*%
x[[i]] i.e. for each i, I want to get a 2x2 matrix
2. Next I want to get x[[1]] + x[[2]] +....
I did following : res=vector("list"); res = sapply(x, function(i) t(x[[i]])
%*% x[[i]])
However above syntax is not giving desired result. Any suggestion please?
______________________________________________
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.
