I think what you want is a meta-heuristic you can use without relying on all the work necessary to code one from the ground. If this is the case, I would recommend you to use the Biased Random Key Genetic Algorithm (BRKGA). Suffices to have in mind the basic notations of Genetic Algorithms, specifically the notion of chromosome and decode function, and there we go. In the section 8.5 of this paper, you can find a decode function applied for a G-VRP variant.
Thanks and regards.