r - partial row-sums in multidimensional arrays -

i have question on how apply r functions multidimensional arrays.

for example, consider operation, reduce entry sum of other entries.

ppl["2012",,,,,1] <- ppl["2012",,,,,1] - ppl["2012",,,,,2] - ppl["2012",,,,,3] - ppl["2012",,,,,4] - ppl["2012",,,,,5] - ppl["2012",,,,,6] - ppl["2012",,,,,7] - ppl["2012",,,,,8] 

while in case subtracting individual values might feasible, prefer vector-oriented approach.

if familiar multidimensional matrix algebra come matrix performs necessary operation when applied, complex given number of dimensions involved.

sum(ppl["2012",,,,,2:8]) not correct solution, sum() returns scalars.

i use loops perform necessary operations, contradicts paradigm of vector-oriented programming.

thanks help!

edit: , here solution original problem, based on andrie's suggestion: ppl[paste(i),land,,,,1] <- ppl[paste(i),land,,,,1] - apply(ppl[paste(i),land,,,,2:8],c(1,2,3),sum)

edited

here example of using apply , sum return sum computed across multi-dimensional table:

mat <- array(1:27, dim=c(3, 3, 3)) 

let's you'd compute sum of third dimension each combination of first 2 dimension.

then code becomes:

apply(mat, c(1,2), sum)       [,1] [,2] [,3] [1,]   30   39   48 [2,]   33   42   51 [3,]   36   45   54