Re: [rules-users] finding matching entries in parallel arrays

The "from" conditional element solves part of my problem: rule "Find matching entry in parallel arrays (alternate)" when $first : ArrayList( ) $second : ArrayList( this != $first ) $fi : Object() from $first $si : Object() from $second eval( $fi == $si ) then System.out.println ( " Found match at index ? : " + $fi + "!" ); end I do want reference equality (==) in my eval. But I understand that object equality would look just like: eval( $fi .equals( $si ) ) Thanks! Aaron On 8/7/07, Mike D <mike.dalaker(a)kewill.com&gt; wrote: > > > Mark, > > Just to be sure I read this correctly: > > eval( $fi == $si ) > > means it's checking objects, not values within the object? > If a compare of values is needed, another eval would have to be written > to > compare temp value. > > Thanks, > Mike > > > Oh, and can we change the documenatation examples please? > > Somthing like... > > rule > when > Team( $team : name == "ManU" ) > $person : Person( favouriteTeam == $team ) > then > System.out.println( $person.getName() + " likes Manchester" ); > end > > rule > when > Team( $team : name == "Chelsea" ) > $person : Person( favouriteTeam != $team ) > then > System.out.println( $person.getName() + " does not like Chelsea > at > all" ); > end > > > > Mark Proctor wrote: > > > > We don't really recommend you assert ArrayLists etc as facts, as they > > have no contextual meaning > > > > $first : ArrayList( ) > > $second : ArrayList( this != $first ) > > $fi Object() from $first > > $si Object from $second > > eval( $fi == $si ) > > > > 'from' allows iteration of lists, so you could potentially do it this > > way, although it doesn't provide an index number for you.... You could > > possibly have a global that as part of a function in eval get > > incremented and that global is available in the consequence. But > you'll > > have to be very careful with concurrency.... Might be easier to have a > > hashmap of indexes where the key is made up of $first and $second. Btw > > > == checks for same instances, not an equality check, is that what you > > wanted? > > > > Mark > > > > Aaron Dixon wrote: > >> My problem boils down to finding matching entries in parallel arrays. > > >> > >> Here is a rule that succesfully does just that: > >> > >> rule "Find matching entry in parallel arrays" > >> when > >> $first : ArrayList( ) > >> $second : ArrayList( this != $first ) > >> $i : Integer( this < $first.size ) > >> eval( $first.get($i) == $second.get($i) ) > >> then > >> System.out.println ( "Found match at index " + $i + "!" ); > >> end > >> > >> > >> To execute this rule, I must insert (assert) the two ArrayList facts > >> as well as at least as many Integer facts as there are items in the > >> ArrayLists. > >> > >> What I don't like about this rule is that > >> > >> (1) I have to assert the Integers > >> (2) I can't support arbitrarily-sized lists in my rules (without > >> asserting that many Integer facts) > >> > >> So -- Is there a better way? > >> > >> What if a future version of Drools supported implicit Number facts > >> that allowed for these kinds of indexing rules? > >> > >> Aaron > >> > >> > >> > >> > >> > ------------------------------------------------------------------------ > >> > >> _______________________________________________ > >> 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 > > > > > > -- > View this message in context: http://www.nabble.com/finding-matching-entries-in-parallel-arrays-tf42251... > > 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 >