Dear Rcppusers,
  I can't figure out what  the following codes do:


int f4(Function pred, List x) {
int n = x.size();
for(int i = 0; i < n; ++i) {
LogicalVector res = pred(x[i]);
if (res[0]) return i + 1;
}
return 0;
}


I investigated it, and understand  applying a function to everypart of  a list then return a LogicalVector, but i can't understand 
if the first element of the LogicalVector is true then return the row index of the list.
Tks!






--

PO SU
mail: desolator88@163.com
Majored in Statistics from SJTU
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