Look at MoveIteratorFactory, that allows you to select those moves JIT
(so without creating all of them like in MoveListFactory).
Also see JUST_IN_TIME vs caching explanation in docs.
Let's continue further questions/discussions on the new mailing list
http://www.optaplanner.org/community/forum.html
hth
On 27-06-14 14:05, DwProd . wrote:
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.s...@gmail.com
<mailto:ge0ffrey.s...@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.s...@gmail.com <mailto:ge0ffrey.s...@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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