Network-based optimization algorithm code for AIS Explorer: Prioritization for Watercraft Inspections

The algorithm submitted here operates on a directed, weighted boat-movement network between lakes and a lake-level infestation status database. It identifies a ranked list of lakes to assign watercraft inspectors to, maximizing the proportion of “risky boats” (boats moving from AIS-infested to uninfested lakes) that are inspected at least once, subject to county-level placement constraints. The algorithm uses an iterative rank-and-remove heuristic based on lake strength (the sum of risky boats entering and leaving each lake). Outputs include, for each lake in a given county, its rank, the marginal proportion of risky boats intercepted if an inspector is placed there, and the cumulative proportion of risky boats intercepted as inspectors are added sequentially. The code was developed to support the AIS Explorer: Prioritization for Watercraft Inspections web application and is provided here for transparency and reuse.