Rcpp loop update variable inside - c++

Question

I am a new user of Rcpp and I am writing an package.
I have defined two functions in one script and try to call one from another in the loop.
One of my function defined as below:
#include <RcppArmadillo.h>
// [[Rcpp::depends(RcppArmadillo)]]
using namespace Rcpp;
using namespace arma;
// [[Rcpp::export]]
double timesTwo(colvec x, NumericVector group, double k,
NumericVector unique_group)
{
vec beta(x.begin(),x.size(),false);
vec Group(group.begin(),group.size(),false);
vec unigroup(unique_group.begin(),unique_group.size(),false);
beta = pow(beta,k);
int g = unigroup.size();
int j = 0;
uvec st ;
double b=0;
for(j = 0; j < g; j++)
{
st = find(Group == unigroup[j]);
b = b + abs(pow(sum(beta.elem(st)),1/k));
}
double s = b;
return s;
}
And the loop I use to to call this function is like below:
XtXi_beta_plus.col(i) = X_MAT * BETA_NEW.col(2*i);
XtXi_beta_minus.col(i) = X_MAT * BETA_NEW.col(2*i+1);
loss_new_1.col(i) = (Y - ited / (ited + exp( -XtXi_beta_plus.col(i))));
loss_new_2.col(i) = (Y - ited / (ited + exp( -XtXi_beta_minus.col(i))));
new_loss(2*i) = accu(loss_new_1.col(i) % loss_new_1.col(i));
new_loss(2*i+1) = accu(loss_new_2.col(i) % loss_new_2.col(i));
z = BETA_NEW.col(2*i);
w = BETA_NEW.col(2*i+1);
// when 88 line was change to BETA_NEW.col(2*i) there is an error
// if you keep use Z, there is no update
// best!
pen_new_positive(i) = as<double>(timesTwo(z,group,k,unique_group));
My question is just like the comment I said in the loop, since I want to update that pen_new_postive(i) based on the BETA_NEW.col(2*i) However when I directly put BETA_NEW.COL(2*i) inside the timesTwo function, no matter how I change input
type of function (colvec or mat or whatever) there is error like below:
cannot convert "const::arma::subview_col<double> to "SEXP" in
initialization"
However when I directly use z in the timesTwo function, there is no update for my z in the loop.
Anyone could give me a hint about how to deal with this?
The full version of my code in second block as below:
#include <RcppArmadillo.h>
#include <math.h>
//#include <omp.h>
using namespace Rcpp;
using namespace arma;
//// [[Rcpp::plugins(openmp)]]
// [[Rcpp::depends(RcppArmadillo)]]
// [[Rcpp::export]]
List minghan21041(NumericMatrix beta_new, NumericVector diff_loss,
NumericVector beta, double step_size, NumericVector y,
double k,
NumericVector group,
NumericVector unique_group,
NumericMatrix X) {
int n = X.nrow(), p=X.ncol() , n1=beta_new.nrow(), p1=beta_new.ncol();
mat X_MAT(X.begin(),n,p,false), BETA_NEW(beta_new.begin(),n1,p1,false);
vec BETA(beta.begin(),beta.size(),false);
vec Y(y.begin(),y.size(),false),
Diff_Loss(diff_loss.begin(),diff_loss.size(),false), iter(p,fill::zeros);
mat XtXi_beta_plus(n,p,fill::zeros);
mat XtXi_beta_minus(n,p,fill::zeros);
vec ited(n,fill::ones);
mat loss_new_1(n,p, fill::zeros),loss_new_2(n,p, fill::zeros);
colvec loss_new_3(n,fill::zeros);
vec new_loss(p1,fill::zeros);
uword index;
vec beta_final(p,fill::zeros);
vec pen_new_positive(p,fill::zeros);
vec pen_new_negative(p,fill::zeros);
double pen_old = 0;
Function timesTwo( "timesTwo" );
double cs=0;
//Col dc(BETA.begin(),p,1);
//pen_old = as<double>(timesTwo(dc,group,k,unique_group));
vec z(p,fill::zeros);
vec w(p,fill::zeros);
int i = 0;
vec XtXi_beta_old = X_MAT*BETA;
loss_new_3= (Y - ited / (ited + exp(-XtXi_beta_old)));
double loss_old_one = accu(loss_new_3%loss_new_3);
//#pragma omp parallel private(i) num_threads(4)
//{
//#pragma omp for ordered schedule(static,1)
for(i= 0; i<p; i++){
//#pragma omp ordered
//{
iter(i) = step_size;
BETA_NEW.col(2*i) = BETA + iter;
BETA_NEW.col(2*i+1) = BETA - iter;
XtXi_beta_plus.col(i) = X_MAT * BETA_NEW.col(2*i);
XtXi_beta_minus.col(i) = X_MAT * BETA_NEW.col(2*i+1);
loss_new_1.col(i) = (Y - ited / (ited + exp( -XtXi_beta_plus.col(i))));
loss_new_2.col(i) = (Y - ited / (ited + exp( -XtXi_beta_minus.col(i))));
new_loss(2*i) = accu(loss_new_1.col(i) % loss_new_1.col(i));
new_loss(2*i+1) = accu(loss_new_2.col(i) % loss_new_2.col(i));
z = BETA_NEW.col(2*i);
w = BETA_NEW.col(2*i+1);
// when 88 line was change to BETA_NEW.col(2*i) there is an error
// if you keep use Z, there is no update, you can source this file and I
//believe there is no other error
// best!
pen_new_positive(i) = as<double>(timesTwo(BETA_NEW.col(2*i),group,k,unique_group));
cs = pen_new_positive(i);
//Rcout << "cs" << cs << std::endl;
Rcout << "cs" << z << std::endl;
//pen_new_negative = as< std::vector<double> >(time(w,group,k,unique_group));
Diff_Loss(2*i) = new_loss(2*i) - loss_old_one + cs;
Diff_Loss(2*i+1) = new_loss(2*i+1) - loss_old_one + cs;
iter(i) = 0;
}
//}
//}
index = Diff_Loss.index_min();
beta_final = BETA_NEW.col(index);
return List::create( _["index"] = wrap(index),
_["Diff_Loss"]= wrap(Diff_Loss[index]),
_["ste"] =wrap(Diff_Loss),
_["beta_new"] = wrap(beta_final),
_["New_LOSS"]= wrap(new_loss[index]),
_["t"] = wrap(pen_new_positive));
}