Looks somewhat different to me; originally there's a fact containing a Collection of letters, not individual Letter() facts, each with its own character. Therefore, you don't have the fact for the initial pattern. -W
2010/12/18 Michael Anstis <[email protected]> > Am I missing something or can't this be achieved purely "in rule":- > > rule "Letter counter" > salience -100 > when > Letter( $c: character ) > not LetterCount( character == $c ) > List( $s : size > 1 ) from collect( Letter( character == $c ) ) > then > LetterCount lc = new LetterCount(); > lc.setCharacter($c); > lc.setDuplications($s); > insert(lc); > end > > rule "Totals" > salience 0 > when > LetterCount($c : character, $s : duplications); > then > System.out.println("Letter " + $c + " has " + $s + " duplications" > end > > 2010/12/18 Wolfgang Laun <[email protected]> > > createCardinality must return a Collection. I think the simplest way of >> solving your problem is to write a simple class LetterCounter implementing >> the counting and a DRL function extracting the collection of Tuples from >> the LetterCounter: >> >> public class LetterCounter extends HashMap<Character,Integer> { >> public static Set<Map.Entry<Character,Integer>> counterSet( >> Collection<Character> l ){ >> return new LetterCounter( l ).entrySet(); >> } >> public LetterCounter( Collection<Character> chars ){ >> super(); >> for( Character c: chars ){ >> Integer count = get( c ); >> put( c, count == null ? 1 : count + 1 ); >> } >> } >> } >> >> rule "count" >> when >> $t: Something( $l: collectionOfLetters ) >> Map.Entry( $key: key, $val: value > 1 ) from >> LetterCounter.counterSet( $l ) >> then >> System.out.println( "letter " + $key + ": " + $val ); >> end >> >> -W >> >> >> On 18 December 2010 12:16, AleBu <[email protected]> wrote: >> >>> >>> Hi, >>> I am new to Drools and do some experiments on it, and encountered on a >>> problem which can't solve for a last few days, so maybe someone can >>> explain >>> what I am doing wrong? >>> I will probably explain my problem with example. Lets say we have a >>> collection of letters like 'a', 'b', 'c', 'a', 'd', 'e', 'c'. And I want >>> to >>> report all letters that are duplicated, but only once providing a number >>> of >>> duplication. In other words, for each letter which is duplicated I need >>> to >>> do a report by saying 'Letter X is duplicated N times. >>> My idea was to create cardinality collection for letters which is a >>> collection of POJOs Tuple where first is letter and second is cound >>> (first >>> and second are properties). I created a function for it >>> createCardinality( >>> Collection letters ) which returns such cardinality info and tried >>> something >>> like: >>> when >>> Something( $letters: collectionOfLetters ) >>> Tuple( $letter: first, $count: second > 1 ) from collect( Tuple() >>> from >>> createCardinality( $letters ) ) >>> then >>> System.out.println( "Letter "+letter+" is duplicated "+$count+" >>> times" ) >>> >>> But I am reported (at least it looks like this) about the problems with >>> my >>> function createCardinality(). Maybe I misunderstood something about usage >>> of >>> FROM? >>> -- >>> View this message in context: >>> http://drools-java-rules-engine.46999.n3.nabble.com/How-to-use-a-result-of-custom-defined-function-in-WHEN-part-tp2110515p2110515.html >>> Sent from the Drools - User mailing list archive at Nabble.com. >>> _______________________________________________ >>> rules-users mailing list >>> [email protected] >>> https://lists.jboss.org/mailman/listinfo/rules-users >>> >> >> >> _______________________________________________ >> rules-users mailing list >> [email protected] >> https://lists.jboss.org/mailman/listinfo/rules-users >> >> > > _______________________________________________ > rules-users mailing list > [email protected] > https://lists.jboss.org/mailman/listinfo/rules-users > >
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