Your reasoning on how to solve the problem is correct. I don't know about your implementation, but my suggestion is: 1. Create a function to calculate the distance between 2 points. I would prefer to create it as a static method in a helper class, but you can define it in the DRL if you prefer: function double distance( long originX, long originY, long actualX, long actualY ) { // return the calculated distance } 2.a. If you want to do it in a single rule, write something like this: when $a: Agent( $x1:x, $y1:y, $r:range) $t1: Tile( $x2: x, $y2 : y, eval( distance( $x1, $y1, $x2, $y2 ) <= $r ) ) not Tile( eval( distance( $x1, $y1, x, y ) < distance( $x1, $y1, $x2, $y2 ) ) ) then end The downside of such approach is that it recalculates the distance many times and the performance would be poor. 2.b. If you want best performance, try a more relational approach with 2 rules: rule "calculate distance" when $a: Agent( $x1 : x, $y1 : y, $r : range ) $t: Tile( eval( distance( $x1, $y1, x, y ) < $r ) ) then assertLogical( new TileInRange( $a, $t, distance( $x1, $y1, x, y ) ) ); end rule "find the closest" when $a: Agent() $tr TileInRange( agent == $a, $tile : tile, $dist : distance ) not TileInRange( agent == $a, distance < $dist ) $t : Tile( this == $tile ) // this last pattern may be removed if you don't need to constrain any other attribute then // do something end Hope it helps Edson 2007/12/6, velven <velven83(a)hotmail.com&gt;: > > > HI, i have a problem > using tileworld model, i'm supposed to write a rule which will cause the > agents to choose the tile in the agent's range which is closest to the > agent. > > so a rough idea is > > when > > agent: Agent(x1:x, y1:y, r:range) > > tile1: Tile(<tile's x to be between (x1+r) and (x1-r)> && <tile's y to be > between (y1+r and y1-r)>) > > tile2: not Tile( < which is closer than the tile1 to agent> ) > > desperately need help, > alternatives tried:: > i tried to use a query to return a list of tiles which is within the > agent's > range then compared which one is closer and other similar implementation, > but this too slow for my simulation... > > I need one single good rule or efficient way of implementing the above > rule > > > then i tried to do multiple constraints too, say x (> 30 && < 40) is > ok > but > x (> > ($x-$r) && < ($x+$r)) gives errors ,due to extra parenthesis? i dunno.. > any > workarounds? > > Thanks! > > > -- > View this message in context: > http://www.nabble.com/How-to-write-a-rule-which-only-fires-for-a-closest-... > Sent from the drools - user mailing list archive at Nabble.com. > > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users > -- Edson Tirelli JBoss Drools Core Development Office: +55 11 3529-6000 Mobile: +55 11 9287-5646 JBoss, a division of Red Hat @ www.jboss.com _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

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!

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! > > > > _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

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! >>> >>> >>> >>> >>> >> _______________________________________________ >> rules-users mailing list >> rules-users(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/rules-users >> >> >> >> > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users > > >