c++ - Rcpp How to change a value directly inside a R List -

i know how values list objet, , how create 1 within c function.

but change value in list given parameter , modification effective when exiting function.

some thing like:

void myfunc(sexp *lst) '    list mylist (lst) // make modification  } 

i need modify list within recursive loop.

thanks in advance daniel

there no magic. assign elements list object, , modify:

r> rcpp::cppfunction("list foo(list l) { list l2 = l[0]; l2[1] = 42; return l2;} ") r> l <- list(list(0,1,2), 2:4, 3.3) r> foo(l) [[1]] [1] 0  [[2]] [1] 42  [[3]] [1] 2  r>  

we pick first element (and know list itself; there predicates testing). in list, set second element. can same returning original modified list:

r> rcpp::cppfunction("list bar(list l) { list l2 = l[0]; l2[1] = 42; return l;} ") r> l <- list(list(0,1,2), 2:4, 3.3) r> bar(l) [[1]] [[1]][[1]] [1] 0  [[1]][[2]] [1] 42  [[1]][[3]] [1] 2   [[2]] [1] 2 3 4  [[3]] [1] 3.3  r>