[rules-users] How to write a rule which only fires for a closest value?

[Darko IVANCAN]

Hi,

Well I assumed you have to have a refence to your agent somehow, and get
your Tiles somehow.

Was just an example, assuming Agent is of class tile.
Correct, an nicer, would be:
when
    agent : Agent();
    closestTile : Tile (closestDistance : distance) from agent.getTiles();
    not Tile(this != closestTile; distance < closestDistance) from
agent.getTiles();
then
   .... System.out.println("Closest Tile "+ closestTile);

The idea here to have agent.getTiles() is to have the Tiles already know
their distance to the agent. ;)

having one engine per agent , in separate threads, could allow the gent
to be a global variable, simplifying the design.

I suggest you to work through the DRools doc, especially the part with
the RETE Algorithm,then you will see, that rules are faster the
Java-If-Then, at least for a serious amount of rules. ;)

Good luck,
Darko Ivancan


On 10/12/2007 09:23, velven wrote:
> Hi, thanks for replying.
> I'll try this implementation of yours,  can you clarify
> this part of your rule:
>   
>> agent : Tile();
>> closestTile : Tile( closestDistance: distance) from agent.getTiles();
>>     
>
> you mean in my Tile class there you should be a method getTiles()? What
> should it return?
> Sorry, I'm very new to Rule engines. 
>
> Actually I'm trying to compare abit on Jess and Drools. Overall my aim is to
> identify efficient way/implementation of writing rules and What kinds of
> problem is more suitable/faster to be implemented in Rule engines than just
> using Java's "if-else". supposed to show some case study.
>
> rules for Case studying now is:
> 1) Agents go for closest tile/hole within its SenseRange
> 2) If exists equal closestDistance, then choose the tile that was created
> first <randomness here is not allowed, need same event occurance during each
> run. Index given during initialisation>
> 3) If target Tile/hole is taken/carried by other Agent, then look for new
> tiles/hole again
> 4) nothing in range => wander
>
> In my java code, I also have a 2D array/Grid which stores the Tiles and
> Agents at their respective location.
> so, in java I can start looking for tiles from the Agent's range 1 to the
> max Range of Agent using "for-loop" 
> its the fastest way by far,(given many tiles in enviroment), since the
> closest Tile can be found first and search stops even if I have other Tiles
> in Range.
> Rule Engine can't do this right? The engine tries to match all the Tiles in
> the WM which takes time.
> I can't make the rule run on incremental range constraint too right?
> PLS correct me if I am wrong about this!
>
> Things I have are Lists of Hole, Agents, Tiles in Java and a Grid
> enviroment.
> current model-> iterates thru Agent list, each Agent executes its action,
> then tries to fire any rules possible.
>
> I guess this is a design question, hope its not too out of place. I needed
> to know if its the way I wrote my rule that made the engine inefficient, or
> this is the kind of problem that Rule engines doesn't perform well on. 
>
> Thanks for any feedback!
>
>
> Darko IVANCAN wrote:
>   
>> Hi,
>>
>> One more thing: You might consider having different engines for
>> different agents, and then having the agent as global variable.
>>
>> Hope this helps,
>> Darko Ivancan
>>
>> On 09/12/2007 18:28, Darko IVANCAN wrote:
>>     
>>> Hi,
>>>
>>> Let's assume we have
>>> class Tile {
>>>     public int x;
>>>     public int y;
>>>     public double distance;
>>> }
>>> For the simplicity of the reader of drop the getters and setters,
>>>
>>> Rule "MyRule"
>>>     agent : Tile();
>>>     closestTile : Tile( closestDistance: distance) from agent.getTiles();
>>>     not Tile(this != closest; distance < clostestDistance) from
>>> agent.getTiles();
>>> ...
>>>
>>> nasty, but should do the "find closest" job.
>>>
>>> Weird, this sounds less like a rules tech/usability question to me than
>>> rather like a desgin question.
>>>
>>> If the answers don'T help, maybe you think about telling us the whole
>>> problem.
>>>
>>> hope this helps,
>>> Darko Ivancan
>>>
>>>
>>> On 06/12/2007 20:03, velven wrote:
>>>   
>>>       
>>>> HI, i have a problem
>>>> using tileworld model, i'm supposed to write a rule which will cause the
>>>> agents to choose the tile in the agent's range which is closest to the
>>>> agent.
>>>>
>>>> so a rough idea is
>>>>
>>>> when
>>>>
>>>> agent: Agent(x1:x, y1:y, r:range)
>>>>
>>>> tile1: Tile(<tile's x to be between (x1+r) and (x1-r)> && <tile's y to
>>>> be
>>>> between (y1+r and y1-r)>)
>>>>
>>>> tile2: not Tile( < which is closer than the tile1 to agent> )
>>>>
>>>> desperately need help,
>>>> alternatives tried::
>>>> i tried to use a query to return a list of tiles which is within the
>>>> agent's
>>>> range then compared which one is closer and other similar
>>>> implementation,
>>>> but this too slow for my simulation... 
>>>>
>>>> I need one single good rule or efficient way of implementing the above
>>>> rule 
>>>>
>>>>
>>>> then i tried to do multiple constraints too, say     x (> 30 && < 40) is
>>>> ok
>>>> but 
>>>>                                                                   x (>
>>>> ($x-$r) && < ($x+$r)) gives errors ,due to extra parenthesis? i dunno..
>>>> any
>>>> workarounds?
>>>>
>>>> Thanks!
>>>>
>>>>
>>>>   
>>>>     
>>>>         
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