On Jul 22, 2009, at 5:07 PM, megh wrote:
Thanks for your suggestions. I need one more thing :
x = y = vector("list")
for (i in 1:5) x[[i]] = rnorm(2); y[[i]] = rnorm(2)
Here I want to get t(x[[i]]) %*% y[[i]] for each i. Can anyone
please help
me?
?lapply
Regards,
Jorge Ivan Velez wrote:
Hi megh,
Perhaps?
# Data
x = vector("list")
for (i in 1:5) x[[i]] = rnorm(2)
# 2x2 matrices
res <- lapply(x, function(a) a %*% t(a) )
res
# Funcion from ?Reduce
add <- function(x) Reduce("+", x)
# Summing up!
add(res)
See ?lapply and ?Reduce for more information.
HTH,
Jorge
On Wed, Jul 22, 2009 at 3:18 PM, megh <megh700...@yahoo.com> 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?
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