[rules-users] To accumulate or not to accumulate

[Bruno Freudensprung]

Hi Wolfgang,

Thanks for your answer.
Sentences are not contiguous (might be some space characters in between) 
but manual annotations cannot overlap sentences (interpret "overlap" in 
terms of Drools Fusion terminology).
If I had an "inside" operator, do you think the following accumulate 
option could be better?

when
*$result : ArrayList() from accumulate ( $s: Sentence(), buildwindows($s))*
*$w : SentenceWindows () **from $result*
     a1 : ManualAnnotation (this *inside *$w)
     a2 : ManualAnnotation (this != a1, this *inside *$w)
then
     ... do something with a1 and a2 since they are "close" to each other
end

Does anyone know something about accumulator parametrization (looking at 
the source code it does not seem to be possible, though)?
Maybe a syntax inspired of operator parametrization could be nice:

     $result : ArrayList() from accumulate ( $s: Sentence(), 
*buildwindows[3]($s)*)

Best regards,

Bruno.

Le 19/08/2011 13:55, Wolfgang Laun a écrit :
> There are some details that one should consider before deciding on a 
> particular implementation technique.
>
>     * Are all Sentences contiguous, i.e., s1.end = pred( s2.start )
>     * Can a ManualAnnotation start on one Sentence and end in the next
>       or any further successor?
>
> As in all problems where constraints depend on an order between facts, 
> performance is going to be a problem with increasing numbers of 
> Sentences and ManualAnnotations.
>
> Your accumulate plan could be a very inefficient approach. Creating 
> O(N*N) pairs and then looking for an overlapping window is much worse 
> than looking at each window, for instance. But it depends on the 
> expected numbers for both.
>
> -W
>
>
>
> 2011/8/19 Bruno Freudensprung <bruno.freudensprung at temis.com 
> <mailto:bruno.freudensprung at temis.com>>
>
>     Hello,
>
>     I am trying to implement rules handling "Sentence",
>     "ManualAnnotation" objects (imagine someone highligthing words of
>     the document). Basically "Sentence" objects have "start" and "end"
>     positions (fields) into the text of a document, and they are
>     Comparable according to their location into the document.
>
>     I need to write rules using the notion "window of consecutive
>     sentences".
>
>     Basically I am not very interested by those "SentenceWindow"
>     objects, I just need them to define a kind of proximity between
>     "ManualAnnotation" objects.
>     What I eventually need in the "when" of my rule is something like:
>
>     when
>         ... maybe something creating the windows
>         a1 : ManualAnnotation ()
>         a2 : ManualAnnotation (this != a1)
>         SentenceWindow (this includes a1, this includes a2)
>     then
>         ... do something with a1 and a2 since they are "close" to each
>     other
>     end
>
>     As I don't know the "internals" of Drools, I would like to have
>     your opinion about what the best "idiom":
>
>         * create all SentenceWindow objects and insert them in the
>           working memory, then write rules against all the facts
>           (SentenceWindow and ManualAnnotation)
>         * implement an accumulator that will create a list of 
>           SentenceWindow object
>
>
>     The first option could look like:
>
>     |||rule "Create sentence windows"
>        when
>           # find 3 consecutive sentences
>           s1 : Sentence()
>           s2 : Sentence(this > s1)
>           s3 : Sentence(this > s2)
>           not Sentence(this != s2 && > s1 && < s3)
>        then
>           SentenceWindow swindow = new SentenceWindow();
>           swindow.setStart(s1.getStart());
>           swindow.setTheend(s3.getEnd());
>           insert(swindow);
>     end|
>
>     ... Then use the first rule "as is".
>
>     The accumulator option could look like (I am not really sure the
>     syntax is correct) :
>
>     when
>     *$result : ArrayList() from accumulate ( $s: Sentence(),
>     buildwindows($s))*
>         a1 : ManualAnnotation ()
>         a2 : ManualAnnotation (this != a1)
>     *SentenceWindows (this includes a1, this includes a2) **from $result*
>     then
>         ... do something with a1 and a2 since they are "close" to each
>     other
>     end
>
>     Is it possible to decide if one way is best than the other?
>
>     And one last question: it is possible to "parametrize" an
>     accumulator (in order to provide the number of sentences that
>     should be put in the windows)?
>     I mean something like:
>
>     when
>         $result : ArrayList() from accumulate ( $s: Sentence(),
>     *buildwindows(3,* $s))
>
>
>     Thanks in advance for you insights,
>
>     Best regards,
>
>     Bruno.
>
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