[rules-users] Using eval in LHS
Greg Barton
greg_barton at yahoo.com
Fri Jul 24 13:04:17 EDT 2009
Try this:
rule "Create Collision Location"
salience 90
no-loop true
when
vehLoc : VehicleLocation()
not CollisionLocation(xway == vehLoc.xway, pos ==
vehLoc.pos, dir == vehLoc.dir, lane == vehLoc.lane)
then
CollisionLocation collisionLoc = new CollisionLocation(vehLoc.getXway(),
vehLoc.getPos(), vehLoc.getDir(), vehLoc.getLane());
insert(collisionLoc);
end
rule "Collect Collided Vehicles"
salience 90
no-loop true
when
vehLoc : VehicleLocation()
$collisionLoc : CollisionLocation(xway == vehLoc.xway, pos ==
vehLoc.pos, dir == vehLoc.dir, lane == vehLoc.lane)
then
collisionLoc.getVehicleLocations().add(vehLoc);
update(collisionLoc);
end
And now, the rule that detects more than three coinciding vehicle locations is simple:
rule "Detect Too Many"
when
CollisionLocation(vehicleLocations.size > 2)
then
...foo...
end
And, if you want to make the execution a bit more efficient, put a reference in VehicleLocation to it's associated CollisionLocation. That way you can have "vehLoc : VehicleLocation(collisionLocation == null)" to reduce partial matches.
--- On Fri, 7/24/09, PriyaSha <nash.8103 at gmail.com> wrote:
> From: PriyaSha <nash.8103 at gmail.com>
> Subject: [rules-users] Using eval in LHS
> To: rules-users at lists.jboss.org
> Date: Friday, July 24, 2009, 10:45 AM
>
> Input:
> 0,0,107,32,0,0,0,10,53320,-1,-1,-1,-1,-1,-1
> 0,0,107,32,0,0,0,10,53320,-1,-1,-1,-1,-1,-1
> 0,0,107,32,0,0,0,10,53320,-1,-1,-1,-1,-1,-1
> 0,0,107,32,0,0,0,10,53320,-1,-1,-1,-1,-1,-1
> 0,0,109,20,0,0,0,19,100644,-1,-1,-1,-1,-1,-1
> 0,0,109,20,0,0,0,19,100644,-1,-1,-1,-1,-1,-1
> 0,0,106,28,0,0,0,26,137745,-1,-1,-1,-1,-1,-1
> 0,0,108,32,0,0,0,67,354281,-1,-1,-1,-1,-1,-1
> 0,0,105,30,0,0,1,94,501089,-1,-1,-1,-1,-1,-1
>
> Problem:
>
> Should find vehicles with same data (if it occurs more than
> thrice).
>
> Though eval in rule 'Detect Accident' results in true,
> consequence is not
> fired.
>
> Output:
>
> Added
> Not Found -- 107---2
> test---2----107
> Not Found -- 107---3
> test---3----107
> Not Found -- 107---4
> test---4----107
> no of veh : 1
> no of veh : 1
> no of veh : 1
> Not Found -- 109---5
> test---1----109
> Not Found -- 109---6
> test---2----109
> Not Found -- 106---7
>
> Please find the DRL below.
>
>
> package com.hp.hpl.CHAOS.LR;
>
> # importing classes
> import java.lang.Integer;
>
> import java.util.ArrayList;
> import java.util.HashMap;
> import java.util.Iterator;
>
> import com.hp.hpl.CHAOS.Rules.VehicleLocation;
>
> global java.lang.String output
>
> declare VehicleLocation
> @role ( event )
> @expires ( 1m )
> end
>
> declare Statistics
> smashedcars : ArrayList
> stopped_cars : ArrayList
> accidents : ArrayList
> collided_at : HashMap
> end
>
> rule "Setup statistics"
> salience 110
> no-loop true
> when
> not( Statistics( ) )
> vehLoc : VehicleLocation()
> then
> Statistics s = new Statistics();
> s.setSmashedcars (new ArrayList());
> s.setStopped_cars (new ArrayList());
> s.getStopped_cars().add(vehLoc);
> s.setCollided_at(new HashMap());
> insert( s );
>
> System.out.println("Added");
> end
>
> rule "Add to stopped cars"
> salience 100
> no-loop true
> when
> vehLoc : VehicleLocation()
> $stat : Statistics ()
> ((not( VehicleLocation(vid ==
> vehLoc.vid) from $stat.getSmashedcars())))
> then
> modify($stat) {
>
> getStopped_cars().add(vehLoc);
> }
> System.out.println("Not Found -- " +
> vehLoc.getVid() + "---" +
> $stat.getStopped_cars().size());
> end
>
>
> rule "Identify Collided Vehicles"
> salience 90
> no-loop true
> when
> vehLoc : VehicleLocation()
> $stat : Statistics ()
> $allStoppedcars : ArrayList( size > 0
> )
> from
> collect ( VehicleLocation(xway == vehLoc.xway, pos ==
> vehLoc.pos, dir == vehLoc.dir, lane == vehLoc.lane) from
> $stat.stopped_cars)
> then
> System.out.println("test" + "---" +
> $allStoppedcars.size() + "----" +
> vehLoc.getVid());
>
> modify($stat) {
>
> setCollided_at(collided_at($allStoppedcars,
> vehLoc.getXway(),
> vehLoc.getPos(), vehLoc.getDir(), vehLoc.getLane()));
> }
> retract (vehLoc);
> end
>
> rule "Detect Accident"
> salience 80
> no-loop true
> when
> vehLoc : VehicleLocation()
> $stat : Statistics ()
>
> eval(collision_occured($stat.getCollided_at()))
> then
> System.out.println("Detect Accident");
> end
>
> function HashMap collided_at(ArrayList stopped_cars, int x,
> int pos, int
> dir, int lane) {
> HashMap collided_at = new HashMap();
> for (Iterator iterator =
> stopped_cars.iterator(); iterator.hasNext(); )
> {
> VehicleLocation vehLoc =
> (VehicleLocation) iterator.next();
> if (vehLoc.getXway() == x
> &&
> vehLoc.getPos() == pos
> &&
> vehLoc.getDir() == dir
> &&
> vehLoc.getLane() == lane) {
>
> int key =
> vehLoc.getVid();
> if
> (!collided_at.containsKey(key)) {
>
> collided_at.put (key, new Integer(1));
>
> continue;
> }
> collided_at.put
> (key,
> ((Integer)collided_at.get(key)).intValue()+1);
> }
> }
> return collided_at;
> }
>
> function boolean collision_occured(HashMap
> collided_vehicles) {
> java.util.Set entries =
> collided_vehicles.entrySet();
> int noOfCollidedVehicles = 0;
> java.util.Iterator iterator =
> entries.iterator();
>
> while ( iterator.hasNext() ) {
> java.util.Map.Entry object =
> (java.util.Map.Entry) iterator.next();
> if ((Integer)object.getValue()
> > 3) {
>
> noOfCollidedVehicles += 1;
> }
> }
>
> if (noOfCollidedVehicles > 0) {
> System.out.println("no of veh :
> " + noOfCollidedVehicles);
> return true;
> }
> return false;
> }
>
> Please let me know what should I correct here.
> --
> View this message in context: http://www.nabble.com/Using-eval-in-LHS-tp24646946p24646946.html
> Sent from the drools - user mailing list archive at
> Nabble.com.
>
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