Re: [rules-users] Multiplying the count of each score rule [planner]

Op 19-12-11 15:04, Patrik Dufresne schreef: > Hi Geoffrey, > > Thanks for your opinion. I will try to implement what I call a > HardAndSoftPriorityScoreDefinition and give it back to the community. > Where is the best place to post a 'patch' ? Create a pull request :) on http://github.com/drools-planner

https://github.com/droolsjbpm/droolsjbpm-build-bootstrap/blob/master/READ... Design wise, I recommend: It's basically about allowing a dynamic number of levels, instead of just 2 (hard and soft). it should not extend AbstractHardAndSoftScore, just extend AbstractScore Because it cannot correctly implement HardAndSoftScore.getSoftScore(); I should just have a Map<Integer, Integer> levelToScoreMap; (no int hardScore or int softScore) hardScore is like level 0. softScore is like level -1. This allows for: softerScore at level -2 harderScore at level 1 Higher level is more important then lower level. The class name should probably contain the word "Level". > > 2011/12/19 Geoffrey De Smet <ge0ffrey.spam(a)gmail.com > <mailto:ge0ffrey.spam@gmail.com>> > > > > Op 14-12-11 18:40, Patrik Dufresne schreef: >> Hi, >> >> I'm still in process to model my planning problem and I have >> some difficulties in defining the correct weight of soft >> constraints. I have soft constraints with different priorities : >> C1, C2, C3, ..., Cn where C1 are higher then C2. Currently, I've >> tried to set different weight for each of them : C1 get higher >> weight. But it's not sufficient since multiple C2 may balance >> one C1. What I really need is to set the priority to every soft >> constraints. >> >> Solution #1 : >> My first thought it to implement a new score definition >> (HardAndSoftPriorityScoreDefinition) having separate soft score >> for each priority. The rule may insert ConstraintOccurence by >> defining the weight and the priority. This solution seems >> elegant but require effort to implement the score definition, >> the score calculation, and other things I don't even know about. > That is the perfect solution to your problem. Start by copy > pasting DefaultHardAndSoftScoreDefinition and work your way from > there. > You'll need to create at least a ScoreDefinition, ScoreCalculator > and Score. > > I've been thinking about adding such a "dynamic" score definition > to planner's build-in scores, > but so far every use case where the developers said they needed > this, it turned out end-users meant it differently: > when you break a 100 C2's, then it's better to break 1 C1 instead... >> >> Solution #2 : >> The other solution is stated in the Drools Planner User Guide : >> >> "Most use cases will also weigh their constraints >> differently, by multiplying the count of each score rule >> with its weight. For example in freight routing, you can >> make 5 broken "avoid crossroads" soft constraints count as >> much as 1 broken "avoid highways at rush hour" soft >> constraint. This allows your business analysts to easily >> tweak the score function as they see fit." >> >> Even tough I don't know how to implement this, it's seems much >> easier to achieve since it's only a rule. Compare to solution >> #1, it's lack the support of soft constraints with same priority >> but different weights. > That text describes plain-old weighting. Say C1 weights 100 and > C2 weights 2, then you can break 50 C2's for every 1 broken C1. > > This is far easier and most of the time end-users actually mean this. > Make exaggerated examples (1000 C2's broken vs 1 C1 broken) and > make your end-users decide what they prefer. If they still prefer > 1000 C2's broken, then you need #1. > > Tip: Sometimes, taking the square of a weight is a neat trick. > In bin packing, say you got > Solution A with 3 CPU and 3 CPU too little = 3² + 3² = 18 > and Solution B with 4 CPU and 2 CPU too little = 4² + 2² = 20 > So the second is worse even though they both miss 6 CPU. > >> >> What is your opinion about both solution. >> >> Is one faster then the other ? >> >> Is it hard to create a new score definition ? >> >> Did anyone ever did this ? >> >> -- >> Patrik Dufresne >> >> >> _______________________________________________ >> rules-users mailing list >> rules-users(a)lists.jboss.org <mailto:rules-users@lists.jboss.org> >> https://lists.jboss.org/mailman/listinfo/rules-users > > -- > With kind regards, > Geoffrey De Smet > > > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org <mailto:rules-users@lists.jboss.org> > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > -- > Patrik Dufresne > > > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users -- With kind regards, Geoffrey De Smet _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users