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

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