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

[Wolfgang Laun]

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 <michael.anstis at gmail.com>

> 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 at gmail.com>
>
> 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 at gmail.com> 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
>>> rules-users at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>
>>
>>
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>
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