Another options is:

head(lapply(a, tail, 2), 2)

On Wed, Jun 24, 2009 at 8:42 PM, Ivo Shterev <idc318@yahoo.com> wrote:

>
> Hello,
>
> I have a question about list indexing. Lets say we have a list of 3 lists,
> each containing 3 different type elements:
>
> > a=replicate(3, list(list(c(1,1,1), diag(3), c(2,2,2))))
> > a
> [[1]]
> [[1]][[1]]
> [1] 1 1 1
>
> [[1]][[2]]
>     [,1] [,2] [,3]
> [1,]    1    0    0
> [2,]    0    1    0
> [3,]    0    0    1
>
> [[1]][[3]]
> [1] 2 2 2
>
>
> [[2]]
> [[2]][[1]]
> [1] 1 1 1
>
> [[2]][[2]]
>     [,1] [,2] [,3]
> [1,]    1    0    0
> [2,]    0    1    0
> [3,]    0    0    1
>
> [[2]][[3]]
> [1] 2 2 2
>
>
> [[3]]
> [[3]][[1]]
> [1] 1 1 1
>
> [[3]][[2]]
>     [,1] [,2] [,3]
> [1,]    1    0    0
> [2,]    0    1    0
> [3,]    0    0    1
>
> [[3]][[3]]
> [1] 2 2 2
>
>
> If anyone can point a direction as to how to obtain (subset) the following
> list from list a:
> > b
> [[1]]
> [[1]][[1]]
>     [,1] [,2] [,3]
> [1,]    1    0    0
> [2,]    0    1    0
> [3,]    0    0    1
>
> [[1]][[2]]
> [1] 2 2 2
>
>
> [[2]]
> [[2]][[1]]
>     [,1] [,2] [,3]
> [1,]    1    0    0
> [2,]    0    1    0
> [3,]    0    0    1
>
> [[2]][[2]]
> [1] 2 2 2
>
> Also, suppose that one wishes to assign the list "b" to the corresponding
> subset of list "a". Is there a way of doing so?
>
> Thanks for the help.
> Ivo
>
> ______________________________________________
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> PLEASE do read the posting guide
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>



-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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