[R] A question on operation on list

[megh]

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?

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 <megh700004 at 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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>>
>> ______________________________________________
>> R-help at 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.
>>
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at 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.
> 
> 

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