Concatenate and Lists in Rcpp - c++

Question

I am just getting starting with Rcpp so this might be a very stupid question. Here is the specific question (context is provided below)
What is the Rcpp equivalent of
odes <- c(A = 1.0, B = 2.0, C = 3.0, D = 4.0, E = 5.0, F = 6.0, G = 7.0)
list(odes)
Context - I am trying to solve a system of Ordinary Differential Equation (ODEs) using the deSolve package's vode solver, but using Rcpp package to write the right hand side of ODEs in a compiled code. The solver expects the function which forms the RHS of ODEs to return a list, specifically in this case the RHS from a .R function (which the solver was able to intergrate successfully) was of the form
> X
[[1]]
9000000.00 -9000000.00 0.00 19993.04 -19993.04 -19993.04 -9000000.00
and I want my .cpp file to spit out odes as a list of similar form.
Any help here would be much appreciated!!
As suggested below, I am pasting the code to show exactly what I am doing
#include <Rcpp.h>
using namespace Rcpp;
// This is a simple example of exporting a C++ function to R. You can
// source this function into an R session using the Rcpp::sourceCpp
// function (or via the Source button on the editor toolbar). Learn
// more about Rcpp at:
//
// http://www.rcpp.org/
// http://adv-r.had.co.nz/Rcpp.html
// http://gallery.rcpp.org/
//
// [[Rcpp::export]]
List odes_gprotein(double t, NumericVector A, NumericVector p) {
NumericVector odes_vec(A.length());
List odes(1);
double Flux1 = p[1] * A[4] * A[5] - p[0] * A[3];
double Flux2 = p[2] * A[5] - p[3];
double Flux3 = p[4] * A[3];
double Flux4 = p[5] * A[1] * A[6];
double Flux5 = p[6] * A[0] * A[3];
double Flux6 = p[7] * A[2];
odes_vec[0] = (Flux4 - Flux5);
odes_vec[1] = (-Flux4 + Flux6);
odes_vec[2] = (Flux5 - Flux6);
odes_vec[3] = (Flux1 - Flux3);
odes_vec[4] = (-Flux1);
odes_vec[5] = (-Flux1 - Flux2);
odes_vec[6] = (-Flux4 + Flux5);
odes = List(odes_vec);
return odes;
}
This function returns (when I supply some value of t, p and A) the following,
> Rcpp::sourceCpp('odes_gprotein.cpp')
> X <- odes_gprotein(0,IC,p)
> str(X)
List of 7
$ : num 9e+06
$ : num -9e+06
$ : num 0
$ : num 19993
$ : num -19993
$ : num -19993
$ : num -9e+06
Whereas, what I need is the X as mentioned above
> X
[[1]]
9000000.00 -9000000.00 0.00 19993.04 -19993.04 -19993.04 -9000000.00
where
str(X)
List of 1
$ : num [1:7] 9e+06 -9e+06 0e+00 2e+04 -2e+04 ...
Thank you for your suggestions!

Answer 1

We still do not really know what you want or tried, but here is a minimal existence proof for you:
R> cppFunction('List mylist(IntegerVector x) { return List(x); }')
R> mylist(c(2:4))
[[1]]
[1] 2
[[2]]
[1] 3
[[3]]
[1] 4
R>
In goes a vector, out comes a list. Have a look at the Rcpp examples and eg the Rcpp Gallery site.

Answer 2

Turns out I was creating the List in a wrong way, I had to remove the following
List odes(1); and List(odes_vec); and return (odes); and had to add the following statement at the end
return Rcpp::List::create(odes_vec);
A better explanation can be found here