com.graphhopper.jsprit.core.problem.constraint

Interface HardActivityConstraint

All Superinterfaces:

Constraint, HardConstraint

All Known Implementing Classes:

ConstraintManager, MaxDistanceConstraint, MaxTimeInVehicleConstraint, PickupAndDeliverShipmentLoadActivityLevelConstraint, ServiceDeliveriesFirstConstraint, ServiceLoadActivityLevelConstraint, ShipmentPickupsFirstConstraint, VehicleDependentTimeWindowConstraints

public interface HardActivityConstraint
extends HardConstraint

Hard constraint that evaluates whether a new activity can be inserted between an activity segment (prevAct,nextAct).

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	HardActivityConstraint.ConstraintsStatus Indicates whether a hard activity constraint is fulfilled or not

Method Summary

Modifier and Type	Method and Description
HardActivityConstraint.ConstraintsStatus	fulfilled(JobInsertionContext iFacts, TourActivity prevAct, TourActivity newAct, TourActivity nextAct, double prevActDepTime) Returns whether newAct can be inserted in between prevAct and nextAct.

Method Detail

fulfilled

HardActivityConstraint.ConstraintsStatus fulfilled(JobInsertionContext iFacts,
                                                   TourActivity prevAct,
                                                   TourActivity newAct,
                                                   TourActivity nextAct,
                                                   double prevActDepTime)

Returns whether newAct can be inserted in between prevAct and nextAct.

When you check activities, you need to understand the following:

Let us assume an existing route;

start, ..., i-1, i, j, j+1, ..., end

When inserting a shipment, two activities will be inserted, pickupShipment k_pick and deliverShipment k_deliver, i.e. jsprit loops through this route (activity sequence) and checks hard and soft constraints and calculates (marginal) insertion costs. For the activity sequence above, it means:

start, k_pick, start+1 (prevAct, newAct, nextAct)
...
i-1, k_pick, i
i, k_pick, j
...

accordingly:
start, k_pick, k_delivery (prevAct, newAct, nextAct)
...
i-1, k_delivery, i
i, k_delivery, j
...

You specify a hard activity constraint, you to check whether for example k_pick can be inserted between prevActivity and nextActivity at all. If so, your hard constraint should return ConstraintsStatus.FULFILLED.
If not, you can return ConstraintsStatus.NOT_FULFILLED or ConstraintsStatus.NOT_FULFILLED_BREAK.

Latter should be used, if your constraint can never be fulfilled anymore when looping further through your route.

Since constraint checking at activity level is rather time consuming (you need to do this thousand/millions times), you can memorize states behind activities to avoid additional loopings through your activity sequence and thus to check your constraint locally (only by looking at prevAct, newAct, nextAct) in constant time.

Parameters:

iFacts - JobInsertionContext provides additional information that might be important when evaluating the insertion of newAct

prevAct - the previous activity, i.e. the activity before the new activity

newAct - the new activity to be inserted in between prevAct and nextAct

nextAct - the next activity, i.e. the activity after the new activity

prevActDepTime - the departure time at previous activity (prevAct) with the new vehicle (iFacts.getNewVehicle())

Returns:

fulfilled if hard constraint is met, other not fulfilled.