Using of G4Accumulable

i want to use G4Accumulable like “G4Accumulable < G4double> fEdep;” in class B1RunAction.hh;
but i need to accumulate N value ( like a table with N dimensions).

std::array<G4Accumulable<G4double>, N> is N is known at compile time.
std::vector<G4Accumulable<G4double>> + a resize member function call on the object if it is variable at runtime.