Re: [rules-users] modifying the problem facts while running the solver - Drools Planner
spinjala wrote
>
> I am new to Drools planner. I have one issue and wanted to understand how
> to resolve it best.
>
> I am trying to use planner to optimize the scheduling of work orders to
> resources. I have certain resources that need to be assigned to a work
> order in a way that maximizes the utilization of the resource. But I have
> a condition where once a resource is scheduled for a workorder, he/she
> shouldn't be scheduled for any other work order again during the same day.
> How do we manage this condition? do we add it as a constraint in the
> drools rule file so that scoring can handle it or do we write a custom
> solver phase to check if a solution has this resource assigned to a WO,
> then skip the resource and proceed with further solution. Please help.
>
See nurseRosteringScoreRules.drl:
// a nurse can only work one shift per day, i.e. no two shift can be
assigned to the same nurse on a day.
rule "oneShiftPerDay"
when
$leftAssignment : ShiftAssignment($leftId : id, $employee :
employee, $shiftDate : shiftDate)
$rightAssignment : ShiftAssignment(employee == $employee, shiftDate
== $shiftDate, id > $leftId)
then
insertLogical(new IntConstraintOccurrence("oneShiftPerDay",
ConstraintType.NEGATIVE_HARD,
1,
$leftAssignment, $rightAssignment));
end
--
View this message in context:
http://drools.46999.n3.nabble.com/modifying-the-problem-facts-while-running-the-solver-Drools-Planner-tp4019099p4019104.html
Sent from the Drools: User forum mailing list archive at Nabble.com.
___
rules-users mailing list
rules-users@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] modifying the problem facts while running the solver - Drools Planner
spinjala wrote
>
> 1) When a solution violates all constraints, does it provide a default
> solution? If so, can it be changed so that it doesn't provide one?
> Otherwise, is there a way to assure that no solution is generated when ALL
> constraints are violated.
>
Let's walk through the code.
Solver.solve() will look for solutions until any of the conditions specified
by the termination configuration are met. These could be based on time, or
score, etc.
In your case, your best solution will have a negative hard score. You would
find this via:
Solution Sol = solver.getBestSolution();
if (Sol.getScore().getHardScore() == 0) {
// no constraints are violated
} else {
// Sol = null
}
spinjala wrote
>
> 2) When a feasible solution is not generated, is it possible to make a
> custom solution as the most relevant solution instead of the generated
> one? For ex. if the solution generated by Drools planner assigned a work
> order WO2 to a resource R1, is it possible to create a custom solution
> that assigns it to, possibly R2?
>
Sharpen your grammar here.
Your first sentence's first clause says that the feasible solution is not
generated, but the last clause references "the generated one."
So who (or what) is making this custom solution?
Remember that the Solution is your class. You are free to write your own
code to fill it on your own via your own code (or user actions).
Jon
--
View this message in context:
http://drools.46999.n3.nabble.com/modifying-the-problem-facts-while-running-the-solver-Drools-Planner-tp4019099p4019154.html
Sent from the Drools: User forum mailing list archive at Nabble.com.
___
rules-users mailing list
rules-users@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] modifying the problem facts while running the solver - Drools Planner
spinjala wrote > > I tried setting the scoreAttained and maximum time allowed to spend in my > termination configuration, but none seems to stop the solver finding the > solution that violates ALL constraints and hence throws a negative hard > score. Is this the only way to do it or any other way is available to > force the solver not to look for a solution when ALL constraints are > violated? > >From Planner's perspective, there are multiple possible solutions. Each solution has a score, a combination of the hard and soft scores, each of which represents the sum of constraint violations. If the scores are <0, then the solution is nonoptimal; and thus, it will keep looking. You might try the termination/maximumUnimprovedStepCount config setting. (see section 6.6.4 of the doc) This stops the solving after a number of steps have been tried without any improvement to the score. Jon -- View this message in context: http://drools.46999.n3.nabble.com/modifying-the-problem-facts-while-running-the-solver-Drools-Planner-tp4019099p4019161.html Sent from the Drools: User forum mailing list archive at Nabble.com. ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] modifying the problem facts while running the solver - Drools Planner
spinjala wrote > > THis is what is happening now with my sample solution that I am writing.. > Once the solver finds that a workorder (WO1) couldn't be assigned to any > resource in the list of resources (due to the constraints)... Well, it's a slightly different problem them. Planner's approach is to solve problems in parallel, where it's not trivial to determine where a given item can be matched. Part of the motivation beyond using Planner is that whether one item fits may be dependent on how the other items are arranged. If workorders are coming in one at a time, why not apply the rules to that item alone -- and that remove it from the planning scenario if it can't be fit? Jon -- View this message in context: http://drools.46999.n3.nabble.com/modifying-the-problem-facts-while-running-the-solver-Drools-Planner-tp4019099p4019264.html Sent from the Drools: User forum mailing list archive at Nabble.com. ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] modifying the problem facts while running the solver - Drools Planner
spinjala wrote > > Once the solver finds that a workorder (WO1) couldn't be assigned to any > resource in the list of resources (due to the constraints), it simply > picks up the 1st resource in the list with highest hard score and assigns > it (even though this assignment breaks all constraints). My question is, > why is it generating a solution by assigning the wrong resource to the > workorder instead of say, throwing a message saying this workorder cannot > be assigned to a resource or something like that. In my opinion, a solver > should generate a solution only when it is possible to generate but not > just assign something that has highest score. I may be wrong but would > really appreciate if you can help here, i am unable to proceed further in > evaluating this product for my project. > Planner perceives an planning variable with the planning value as being "uninitialized", not as "unassigned". This is due to https://issues.jboss.org/browse/JBRULES-3317 Add a planning value resource that represents "unassigned". Then add a hard constraint rule that gets trigged if something is assigned to that planning value. Give a lower weight than 2 entities being assigned to the same value and make the 2 entities being assigned to the same value not trigger if they are assigned to that "unassigned" value. -- View this message in context: http://drools.46999.n3.nabble.com/modifying-the-problem-facts-while-running-the-solver-Drools-Planner-tp4019099p4019273.html Sent from the Drools: User forum mailing list archive at Nabble.com. ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] modifying the problem facts while running the solver - Drools Planner
typo: Planner perceives an planning variable with the planning value *null* as being "uninitialized", not as "unassigned". This is due to https://issues.jboss.org/browse/JBRULES-3317 -- View this message in context: http://drools.46999.n3.nabble.com/modifying-the-problem-facts-while-running-the-solver-Drools-Planner-tp4019099p4019274.html Sent from the Drools: User forum mailing list archive at Nabble.com. ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
