Hi Geoffrey,<div><br></div><div>Thanks for your opinion. I will try to implement what I call a <span style="color:rgb(51,51,51);font-family:'Lucida Grande',Geneva,Verdana,Arial,sans-serif;font-size:12px;line-height:18px;text-align:justify">HardAndSoftPriorityScoreDefini</span><span style="color:rgb(51,51,51);font-family:'Lucida Grande',Geneva,Verdana,Arial,sans-serif;font-size:12px;line-height:18px;text-align:justify">tion and give it back to the community. Where is the best place to post a 'patch' ?</span><br>
<br><div class="gmail_quote">2011/12/19 Geoffrey De Smet <span dir="ltr"><<a href="mailto:ge0ffrey.spam@gmail.com">ge0ffrey.spam@gmail.com</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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Op 14-12-11 18:40, Patrik Dufresne schreef:
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<div>Hi,</div>
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>Solution #1 :</div>
<div>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.</div>
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That is the perfect solution to your problem. Start by copy pasting
<font><font color="#333333" face="'Lucida Grande', Geneva, Verdana,
Arial, sans-serif">DefaultHardAndSoftScoreDefinition and work
your way from there.<br>
You'll need to create at least a ScoreDefinition,
ScoreCalculator and Score.<br>
<br>
I've been thinking about adding such a "dynamic" score
definition to planner's build-in scores,<br>
but so far every use case where the developers said they needed
this, it turned out end-users meant it differently:<br>
when you break a 100 C2's, then it's better to break 1 C1
instead...<br>
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<div>Solution #2 :</div>
<div>The other solution is stated in the Drools Planner
User Guide : </div>
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<div style="font-size:12px;line-height:18px"><font color="#333333" face="'Lucida Grande', Geneva,
Verdana, Arial, sans-serif">
<div>"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."</div>
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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.</div>
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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.<br>
<br>
This is far easier and most of the time end-users actually mean
this.<br>
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.<br>
<br>
Tip: Sometimes, taking the square of a weight is a neat trick.<br>
In bin packing, say you got<br>
Solution A with 3 CPU and 3 CPU too little = 3² + 3² = 18<br>
and Solution B with 4 CPU and 2 CPU too little = 4² + 2² = 20<br>
So the second is worse even though they both miss 6 CPU.<br>
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<div style="font-size:12px;line-height:18px">What is
your opinion about both solution.</div>
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<div style="font-size:12px;line-height:18px">
Is one faster then the other ? </div>
<div style="font-size:12px;line-height:18px"><br>
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<div><span style="font-size:12px;line-height:18px">Is
it hard to create a new score definition ?</span></div>
<div><span style="font-size:12px;line-height:18px"><br>
</span></div>
<div><span style="font-size:12px;line-height:18px">Did
anyone ever did this ? </span></div><span class="HOEnZb"><font color="#888888">
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-- <br>
Patrik Dufresne<br>
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</font></span></blockquote><span class="HOEnZb"><font color="#888888">
<br>
<pre cols="72">--
With kind regards,
Geoffrey De Smet</pre>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br>Patrik Dufresne<br>
</div>