ML-based LS Operator Selection

[inboxedshoe]

I've been looking into the GoogleOR documentation and trying to find a way to change or keep the local search operator being used at any given step. I looked into search monitors and then the metaheuristic models but couldn't seem to find a way to select the operator to use mid-way. I'm not certain if this route is feasible as the examples don't show a method of switching LS Operators either.

The main concern was to also be able to use the routing model. I looked into the simplest method of restarting the search or setting up a new one every time with a 1-step limit but that caused unneeded overhead and was often buggy, especially when accessing the routing model through the python wrapper.

Any thoughts on other steps I can try to customize the model? I'm obviously quite new to GoogleOR as a whole and hoping here would be a good place to get a proper foothold.

[Mizux]

Do you mean changing this parameter during the search ?

or-tools/ortools/constraint_solver/samples/vrp_with_time_limit.py

Lines 99 to 100 in b37d9c7

	search_parameters.local_search_metaheuristic = (
	routing_enums_pb2.LocalSearchMetaheuristic.GUIDED_LOCAL_SEARCH)

What about running in parallel the same model with different LS metaheuristic ?

[inboxedshoe]

There's that But I also want to be able to change the local search (ex. do 1 step 2-opt, check result, continue 2-opt or change to 3-opt etc). This technically would make a parallel approach invalid.

Which is basically in this part of the search parameters:

local_search_operators {

use_relocate: true

use_relocate_pair: true

use_exchange: true

use_cross: true

use_two_opt: true

use_or_opt: true

use_lin_kernighan: true

use_make_active: true

use_make_inactive: true

use_swap_active: true

use_path_lns: true

use_inactive_lns: true

}

[inboxedshoe]

As an update, I tried accessing the routing model's underlying solver, adding a decision builder, and calling newSearch but to no response from the code. I'm guessing that function isn't available to call.