R help - Apr 2011 - Help in splitting ists into sub-lists

Dear List,

Let's say I have a list whose components are 2 matrices (as exemplified in
the "mylist" object below). I'd like to create a list with
components being
4 matrices based on an logical index vector. is there a way to simplify what
I'm doing to obtain the results in "mylist2"? I'd like
something that would
work on an arbitrary number of elements in "mylist".

mylist <- list(matrix(1:9,3,3), matrix(10:18,3,3))
index1 <- c(TRUE,FALSE,TRUE)
index2<- c(FALSE,TRUE,TRUE)
mylist2 <- list(mylist[[1]][,index1],
                      mylist[[1]][,index1==FALSE],
                      mylist[[2]][,index2],
                      mylist[[2]][,index2==FALSE])

Thanks in advance,
Axel.

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Hi:

here is one solution. Not so elegant but maybe it will give you some ideas:

mylist1<-rep(mylist,c(2,2))
a<-matrix(c(index1,!index1,index2,!index2),ncol=4)
mylist2<-list()
for (i in 1:4)
{
mylist2[[i]]<-mylist1[[i]][,a[,i]]
}

mylist2

Andrija

On Sun, Apr 3, 2011 at 6:56 PM, Axel Urbiz <axel.urbiz@gmail.com> wrote:
> Dear List,
>
> Let's say I have a list whose components are 2 matrices (as exemplified
in
> the "mylist" object below). I'd like to create a list with
components being
> 4 matrices based on an logical index vector. is there a way to simplify
> what
> I'm doing to obtain the results in "mylist2"? I'd like
something that would
> work on an arbitrary number of elements in "mylist".
>
> mylist <- list(matrix(1:9,3,3), matrix(10:18,3,3))
> index1 <- c(TRUE,FALSE,TRUE)
> index2<- c(FALSE,TRUE,TRUE)
> mylist2 <- list(mylist[[1]][,index1],
>                      mylist[[1]][,index1==FALSE],
>                      mylist[[2]][,index2],
>                      mylist[[2]][,index2==FALSE])
>
> Thanks in advance,
> Axel.
>
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>
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