Hi Hui,
Ssee ?Reduce for more details. You might try something along the lines of
> mymean <- function(x) Reduce("+", x)/length(x)
> add(b)
[,1] [,2]
[1,] 10.33333 12.33333
[2,] 11.33333 13.33333
HTH,
Jorge
On Thu, Mar 24, 2011 at 11:07 AM, Hui Du <> wrote:
> Hi All,
>
> Suppose I have data like
>
> b[[1]] = matrix(1:4, 2, 2)
> b[[2]] = matrix(10:13, 2, 2)
> b[[3]] = matrix(20:23, 2, 2)
>
> [[1]]
> [,1] [,2]
> [1,] 1 3
> [2,] 2 4
>
> [[2]]
> [,1] [,2]
> [1,] 10 12
> [2,] 11 13
>
> [[3]]
> [,1] [,2]
> [1,] 20 22
> [2,] 21 23
>
> Now I want to calculate the mean of each cell across the
> list. For example mean of (b[[1]][1,1], b[[2]][1,1], b[[3]][1,1]), mean of
> (b[[1]][1,2], b[[2]][1,2], b[[3]][1,2]) etc. e.g. mean of (1, 10, 20), mean
> of(3, 12, 22). Could somebody tell me how to do it? Thank you in advance.
>
> HXD
>
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>
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