[Rcpp-devel] translate an R vectorized loop with three logical conditions to C++

[Nelson Villoria]

I am new to this list, so I hope this is the right place to ask this 
question. I am trying to translate the R vectorized loop below to C++ in 
order to speed up my calculations:

Let:
 > n1
  [1] 1 1 2 2 2 3 3 4 4 4 5 5 5 5 6 6 6 7 7 8 8 8 9 9
 > n2
  [1] 2 4 1 3 5 2 6 1 5 7 2 4 6 8 3 5 9 4 8 5 7 9 6 8
 > w1w1
  [1] 0.2500000 0.2500000 0.1111111 0.1111111 0.1111111 0.2500000 0.2500000
  [8] 0.1111111 0.1111111 0.1111111 0.0625000 0.0625000 0.0625000 0.0625000
[15] 0.1111111 0.1111111 0.1111111 0.2500000 0.2500000 0.1111111 0.1111111
[22] 0.1111111 0.2500000 0.2500000

My vectorized loop is:

     tWSWS.k <- lapply(c(1:length(n1)), function(.n1){
       lapply(c(1:length(n2)), function(.n2){
         if(.n1!=.n2){
          w1w1[n1==.n1 & n2==.n2]
        }})})

result=sum(unlist(tWSWS.k))

Could you help me with this translation or at least point me out to some 
reference/example?

Thanks!

Nelson

-- 
Nelson Villoria
Research Assistant Professor
Center for Global Trade Analysis
Department of Agricultural Economics
Purdue University
403 W. State St
West Lafayette IN 47906
765.494.4303
nvillori at purdue.edu