RoutingBlocks: An Open-Source Python Package for Vehicle Routing Problems with Intermediate Stops.

We introduce RoutingBlocks, a versatile open-source Python package designed to simplify the development of algorithms for vehicle routing problems with intermediate stops (VRPIS). The package offers a variety of modular algorithmic components and optimized data structures crafted specifically to address key challenges of VRPIS, such as a lack of exact constant-time move evaluations and difficult station visit decisions. By using a unified solution and instance representation that abstracts problem-specific behavior (for example, constraint checking, move evaluation, and cost computation) into well-defined interfaces, RoutingBlocks maintains a clear separation between algorithmic components and specific problem configurations, thus allowing the application of the same algorithm to a variety of problem settings. Leveraging an efficient C++ implementation for performance-critical core elements, RoutingBlocks combines the high performance of C++ with the user-friendliness and adaptability of Python, thereby streamlining the development of effective metaheuristic algorithms. As a result, researchers using RoutingBlocks can focus on their algorithms' core features, allocating more resources to innovation and advancement in the VRPIS domain. History: Accepted by Ted Ralphs, Area Editor for Software Tools. This paper has been accepted for the INFORMS Journal on Computing Special Issue on Software Tools for Vehicle Routing. [ABSTRACT FROM AUTHOR]