Sorry, the above should have been

> mymean <- function(x) Reduce("+", x)/length(x)
> mymean(b)
         [,1]     [,2]
[1,] 10.33333 12.33333
[2,] 11.33333 13.33333

Apologies for the noise.

Best,
Jorge


On Thu, Mar 24, 2011 at 3:54 PM, Jorge Ivan Velez <> wrote:

> 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
>>
>>        [[alternative HTML version deleted]]
>>
>> ______________________________________________
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>> 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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