Re: [rules-users] [Drools Planner] Multi depot CVRP / CVRPTW

Geoffrey De Smet Mon, 04 Mar 2013 07:34:46 -0800

Op 04-03-13 13:39, Mats Norén schreef:

Hi Geoffrey,

After a long period away from this problem I've come back to it and I'm feeling a bit lost :-)

Could you elaborate on how to best model the rules and domain objects. I've looked at the nurse rostering example but didn't find any clues on how to proceed.

My first stab on this uses the following rules:

rule "arrivalTime"
    when
        $vehicle : VrpVehicle()
        $customer : VrpCustomer(
                vehicle == $vehicle,
                $arrivalTime : arrivalTime)
    then
        insertLogical(new VrpCustomerVisitArrivalTime($customer, $arrivalTime));
end

rule "arrivalWithinTimeWindow"
    when
        VrpCustomerVisitArrivalTime($c : customer, $a : arrival)
        not CustomerTimeWindow(customer == $c, $a > startTime, $a < endTime)
    then
        insertLogical(new IntConstraintOccurrence("arrivalWithinTimeWindow", ConstraintType.HARD, -$a, $c))
end

I've added a method arrivalTime to VrpCustomer that walks the VrpAppearances to the Depot and accumulates the travel time between each appearance. (I'm using GraphHopper and the OpenStreetMap roadnetwork). This works similar to the getDistance(VrpLocation location).

What I didn't grasp is how the rule in your example is using the CustomerTimeWindow? I'm assuming the CustomerTimeWindow is a property on VrpCustomer?

The example only does the capacitated vehicle routing problem (VRP + capacity limits), not the windowed vehicle routing problem.

Should I add each CustomerTimeWindow as a fact in the VrpSchedule.getProblemFacts?

Yes, so your score rules can exploit it.
Also, you 'll want to make sure that your score rule penalize "the number of minutes that a time window isn't met".

Btw, I'm using drools-planner 6.0.0-SNAPSHOT.

Regards,
Mats

ps.

I like the new name OptaPlanner.

ds.

On Tue, Nov 20, 2012 at 1:54 PM, Mats Norén <[email protected]> wrote:

Ok, so on the first rule should fire for all occurrences of a Customer since each Customer should have at least one visit?

It's not another planning variable,
instead,
do something like

when
...
then
insertLogical(new CustomerVisitArrivalTime(...));
end

when
CustomerVisitArrivalTime($c : customer, $a : arrival)
not CustomerTimeWindow(customer == $c, $a > start, $a < end)
then
insertLogical(new IntConstraintOccurrence(...))
end

See nurseRosteringScoreRules.drl for an example of use of
insertLogical's like that

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Btw, thanks for your help and thanks for a great product!

Regards,

Mats
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Re: [rules-users] [Drools Planner] Multi depot CVRP / CVRPTW

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