Re: [rules-users] How to use a result of custom defined function in WHEN part?

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 <wolfgang.laun(a)gmail.com&gt; 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 <aleboo(a)gmail.com&gt; 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-o... >> 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 >> > > > _______________________________________________ > 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