Thank you Dimitris!
I have 3D arrays of the same dimensions, so Reduce worked...

Best,
Eleni


On Thu, Mar 4, 2010 at 5:13 PM, Dimitris Rizopoulos <
d.rizopoulos@erasmusmc.nl> wrote:

> do these lists contain 3D arrays of the same dimensions? If yes, then you
> could use
>
> Reduce("+",  pred.svm[[i]])[1,2,5]
>
> otherwise a for-loop will also be clear and efficient, e.g.,
>
>
> W <- pred.svm[[i]][[1]][1,2,5]
> for (j in 2:20) {
>    W <- W + pred.svm[[i]][[j]][1,2,5]
> }
>
>
> I hope it helps.
>
> Best,
> Dimitris
>
>
>
> On 3/4/2010 4:02 PM, Eleni Christodoulou wrote:
>
>> Dear list,
>>
>> I have some difficulty in manipulating list elements. More specifically, I
>> am performing svm regression and have a list of lists, called pred.svm.
>> The
>> elements of the second list are 3D arrays. Thus I have pred.svm[[i]][[j]],
>> with 1<=i<=5 and 1<=j<=20.
>> I want to take the sum of the elements a specific array dimension across
>> all
>> j, for one i. Mathematically speaking, I want to calculate *W* as:
>>
>>           *W = pred.svm[[i]][[1]][1,2,5] + pred.svm[[i]][[2]][1,2,5]+
>> pred.svm[[i]][[3]][1,2,5]+...+ pred.svm[[i]][[20]][1,2,5]*
>>
>> I have tried to apply the *lapply() *function but it seems that its
>> arguments can only be vector elements of a list...Do I need to convert the
>> array data to vector data?
>>
>> Any advice would be very welcome!
>>
>> Thanks a lot,
>> Eleni
>>
>>        [[alternative HTML version deleted]]
>>
>>
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>>
>>
> --
> Dimitris Rizopoulos
> Assistant Professor
> Department of Biostatistics
> Erasmus University Medical Center
>
> Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
> Tel: +31/(0)10/7043478
> Fax: +31/(0)10/7043014
>

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