[rules-users] Coarse Grained Moves

Fri Jun 27 08:05:41 EDT 2014

Thanks a lot, yeah nearBySelection is probably what I would need, too bad
it's not out yet :(

As for the custom MoveListFactory, I found out what I'm trying to do has an
off the charts complexity. It basically has to find all subsets of planning
variables of a given size (combinations with repetition) which is the
number of entities I want to move at once... Worst case has a complexity of
something like O(4^n/sqrt(pi n))... It gets unmanagable pretty soon
unfortunately.

I'm not sure what I'll be doing but it seems like I'll have to do without
those constraints at first... Thanks again for your help however !

Best regards,

Woody

2014-06-25 13:18 GMT+02:00 Geoffrey De Smet <ge0ffrey.spam at gmail.com>:

>
> On 25-06-14 12:58, DwProd . wrote:
>
> Thanks a lot for your answer !
>
>  1) I don't think pillar based moves are what I'm looking for, except if
> I can select a pillar based on a Problem Fact (its service in my case) and
> then spread the different entities of the pillar on the available hosts
> (basically setting possibly different planning variables for the entities
> of the pillar).
>
>  2) cartesianProductMoveSelector seem more like it, but the number of
> moves to combine is somewhat static is it not ? I can't for instance
> specify in a Planning Entity (using a property) that its move should be
> combined with n other moves of processes of the same type ?
>
> That would be nearBySelection... (note: the name might change before I
> implement).
> You need to be able to tell optaplanner that processes of the same type
> are "near" (~related) to each other and should be moved together.
> As stated before, I am working on this for 6.2.
>
>
>  3) I feel like my usecase is complicated enough to have to resort to
> that if there is no built in way to handle it... Does this work by
> implementing a MoveListFactory, or a CompositeMove ? I don't think I quite
> get the difference to be honest...
>
> If you write a custom MoveListFactory (or MoveIteratorFactory), you could
> still opt to go with the build-in moves (such as ChangeMove) or
> combinations of those with CompositeMove. However, because those build-in
> moves require reflection stuff (VariableDescriptor etc), it's probably
> easier to just to write a domain-specific Move.
> See the examples that have custom moves.
>
>
>  Thanks again for your time,
>
>  Cheers,
>
>  Woody
>
>
> 2014-06-25 9:37 GMT+02:00 Geoffrey De Smet <ge0ffrey.spam at gmail.com>:
>
>>  1) There's 2 course grained moves out of the box in 6.1.0.CR1:
>> pillarChangeMove and pillarSwapMove.
>> And in 6.1.0.CR1 they also include subpillars (which is important).
>>
>> http://docs.jboss.org/drools/release/latest/optaplanner-docs/html_single/index.html#pillarChangeMoveSelector
>> Start with trying those.
>>
>> 2) Then look into cartesianProduct selection and mimic selection (see
>> docs).
>> The <cartesianProductMoveSelector> allows you to combine to existing
>> moves into a new one.
>> The mimic selection allows you to make sure that those 2 moves change the
>> same entity (if needed), but a different variable of course.
>> I am working on nearBySelection for 6.2 to allow it to select 2 entities
>> that are somehow "nearBy" to each other (for example in the same service
>> etc).
>>
>> 3) If the above don't help enough, there's always custom moves (see
>> docs): total freedom, but the devil is in the details :)
>>
>>
>> On 24-06-14 01:58, DwProd . wrote:
>>
>>  Hello there,
>>
>>  I'm pretty new to OptaPlanner, and I must say I'm really impressed with
>> the maturity of it all. Great software with a great documentation !
>>
>>  I've been working on a variation of the Cloud Balancing example, with a
>> few differences, which make it look like the Machine Reassignment problem
>> as well :
>>
>>  - Some processes are already placed and are immovable (using a
>> Selection Filter checking a boolean property of the planning entity)
>> - The Computer (the planning variable) is nullable (basically this is
>> Multiple Muti-Dimensional Knapsack problem) which means I added a soft
>> constraint penalty for processes with a null host.
>> - Processes can only be of a few classes (which I called services, a
>> Problem Fact). Processes of a given service type have a certain amount of
>> required cpu and ram.
>>
>>  Taking these elements into account, I do get very good results with
>> OptaPlanner. However, the following constraints always put me into a score
>> trap :
>>
>>  - For some services, processes work in groups. For instance, if groups
>> are of size 3, having 7 processes is not any better than having 6
>> processes. If there were already 2 processes (immovable and placed), I
>> should only add 4 processes and not 5, even if there are enough resources.
>> For this constraint, I have tried using a rule (medium constraint)
>> accumulating processes of that service and using the modulo operator with
>> the group size.
>> - Some services are dependant on one another. For instance, I know that
>> if I have n1 groups of processes of the service 1, I require
>> Math.ceil(2.5*n1) groups of processes of the service 2. I have implemented
>> this similarly with a medium constraint...
>>
>>  With any (or both) of these constraints, little to no processes of the
>> concerned services are added and I fail to reach a good solution. I have
>> tried benchmarking with several local search methods and various
>> parameters, but all give the same results...
>>
>>  I feel like the next logical step would be to used the often mentioned
>> in the documentation "Coarse Grained Moves" but I fail to locate any simple
>> example. The Nurse Rostering example seems to use that technique to some
>> extent but it seems like an overly complicated example, is it not.
>>
>>  Thank you very much for reading this far, if you have any question,
>> guideline, or just a trick, I'd be absolutely delighted to hear from you !
>>
>>  Cheers,
>>
>>  Woody
>>
>>
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