I'm not sure I understand your question: a[[2]] is a matrix.

> a <- list(matrix(1:6,2),matrix(5:10,2))
> is.matrix(a[[2]])
TRUE
x = a[[2]]
> is.matrix(x)
TRUE
> x+2
      [,1] [,2] [,3]
[1,]  7     9   11
[2,]  8    10  12
> a[[2]] + 2
      [,1] [,2] [,3]
[1,]  7     9   11
[2,]  8    10  12

What else do you need?

Michael Weylandt

On Wed, Aug 24, 2011 at 2:28 PM, Chee Chen <chee.chen@yahoo.com> wrote:

> Dear All,
> As always, I appreciate all your help.
> I would like to know the easiest way to convert each of the homogeneous
> elements of a numeric list into a matrix. Each element of this list is also
> a list such that when displayed, looks like a 2-by-3 matrix , I would like
> to convert each of them into a matrix, without changing the double index of
> each entry.
>
> Suppose:
> a<- vector("list",2)
> > a[[1]]
>           [,1]  [,2]  [,3]
> [1,]      1     2      0
> [2,]     3      4      5
>
> > a[[2]]
>           [,1]  [,2] [,3]
> [1,]      5     6    9
> [2,]      7    8      10
>
> >is.list(a[[1]])
> True
>
> Target: I would like to convert a[[2]] into a matrix, keeping the double
> index, into
> > mat1
>           [,1]  [,2] [,3]
> [1,]      5     6   9
> [2,]      7    8    10
>
> The list I have is huge and so is each of its elements, and do not want to
> use unlist because I do not understand it fully.
> Thank you,
> Chee
>
>
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>
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> and provide commented, minimal, self-contained, reproducible code.
>

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