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

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