Question

我无法使用路由参数运行解决方案，因为该方法不接受默认的RoutingSearchParameters，因为实例为空（每个字段均设置为0）。

这是我创建实例的方式：

// final var p = RoutingSearchParameters.newBuilder().build(); Both don't work
final var p = RoutingSearchParameters.getDefaultInstance();
final var s = routing.solveWithParameters(p);

这是错误（发生在每个字段中）：

E0717 20:27:26.682358  6108 routing.cc:1886] Invalid RoutingSearchParameters: Invalid cheapest_insertion_first_solution_neighbors_ratio: 0

有没有办法解决这个问题而无需手动设置每个字段？

Answer 1

所有默认参数在此处可见：

https://github.com/google/or-tools/blob/45770b833997f827d322e929b1ed4781c4e60d44/ortools/constraint_solver/routing_parameters.cc#L45

      "first_solution_strategy: AUTOMATIC "
  "use_unfiltered_first_solution_strategy: false "
  "savings_neighbors_ratio: 1 "
  "savings_max_memory_usage_bytes: 6e9 "
  "savings_add_reverse_arcs: false "
  "savings_arc_coefficient: 1 "
  "savings_parallel_routes: false "
  "cheapest_insertion_farthest_seeds_ratio: 0 "
  "cheapest_insertion_first_solution_neighbors_ratio: 1 "
  "cheapest_insertion_ls_operator_neighbors_ratio: 1 "
  "local_search_operators {"
  "  use_relocate: BOOL_TRUE"
  "  use_relocate_pair: BOOL_TRUE"
  "  use_light_relocate_pair: BOOL_TRUE"
  "  use_relocate_subtrip: BOOL_TRUE"
  "  use_relocate_neighbors: BOOL_FALSE"
  "  use_exchange: BOOL_TRUE"
  "  use_exchange_pair: BOOL_TRUE"
  "  use_exchange_subtrip: BOOL_TRUE"
  "  use_cross: BOOL_TRUE"
  "  use_cross_exchange: BOOL_FALSE"
  "  use_relocate_expensive_chain: BOOL_TRUE"
  "  use_two_opt: BOOL_TRUE"
  "  use_or_opt: BOOL_TRUE"
  "  use_lin_kernighan: BOOL_TRUE"
  "  use_tsp_opt: BOOL_FALSE"
  "  use_make_active: BOOL_TRUE"
  "  use_relocate_and_make_active: BOOL_FALSE"  // costly if true by default
  "  use_make_inactive: BOOL_TRUE"
  "  use_make_chain_inactive: BOOL_FALSE"
  "  use_swap_active: BOOL_TRUE"
  "  use_extended_swap_active: BOOL_FALSE"
  "  use_node_pair_swap_active: BOOL_TRUE"
  "  use_path_lns: BOOL_FALSE"
  "  use_full_path_lns: BOOL_FALSE"
  "  use_tsp_lns: BOOL_FALSE"
  "  use_inactive_lns: BOOL_FALSE"
  "  use_global_cheapest_insertion_path_lns: BOOL_TRUE"
  "  use_local_cheapest_insertion_path_lns: BOOL_TRUE"
  "  use_global_cheapest_insertion_expensive_chain_lns: BOOL_FALSE"
  "  use_local_cheapest_insertion_expensive_chain_lns: BOOL_FALSE"
  "}"
  "relocate_expensive_chain_num_arcs_to_consider: 4 "
  "heuristic_expensive_chain_lns_num_arcs_to_consider: 4 "
  "local_search_metaheuristic: AUTOMATIC "
  "guided_local_search_lambda_coefficient: 0.1 "
  "use_depth_first_search: false "
  "use_cp: BOOL_TRUE "
  "use_cp_sat: BOOL_FALSE "
  "continuous_scheduling_solver: GLOP "
  "mixed_integer_scheduling_solver: CP_SAT "
  "optimization_step: 0.0 "
  "number_of_solutions_to_collect: 1 "
  // No "time_limit" by default.
  "solution_limit: 0x7fffffffffffffff "             // kint64max
  "lns_time_limit: { seconds:0 nanos:100000000 } "  // 0.1s
  "use_full_propagation: false "
  "log_search: false "
  "log_cost_scaling_factor: 1.0 "
  "log_cost_offset: 0.0";

Answer 2

如评论所指出：实例化RoutingSearchParameters类的正确方法是导入com.google.ortools.constraintsolver.main，然后使用方法main.defaultRoutingSearchParameters()。

RoutingSearchParameters的默认实例不起作用

2 个答案: