I think Greg Biegel wrote:
>
> (defrule avgweight
> (SmartCouch_LoadCellSensor1_MassEvent_Bean (mass ?mass1))
> (SmartCouch_LoadCellSensor2_MassEvent_Bean (mass ?mass2))
> (SmartCouch_LoadCellSensor3_MassEvent_Bean (mass ?mass3))
> (SmartCouch_LoadCellSensor4_MassEvent_Bean (mass ?mass4))
> =>
> (bind ?*totalweight* (+ ?mass1 ?mass2 ?mass3 ?mass4))
> (bind ?*averageweight* (/ ?*totalweight* 4))
> (bind ?*averageweight* (- ?*averageweight* 0.5))
> )
>
> However, each bean is not necessarily updated between each firing of the
> engine (as each bean is updated individually, it calls Rete.run()). What I
> am worried about is that this rule will only fire if ALL beans have had
> their mass field updated since the last firing, so I am unable to get a
> current average weight reading to use in the LHS of other rules in the same
> firing.
No, it will actually fire any time any one of them changes, so maybe
that's good enough.
Defqueries are tough in Jess 6. They get a lot easier in Jess 7. But
there are examples in section 2.9 of the manual. You'd want your query
to look like
(defquery all-sensors
(SmartCouch_LoadCellSensor1_MassEvent_Bean)
(SmartCouch_LoadCellSensor2_MassEvent_Bean)
(SmartCouch_LoadCellSensor3_MassEvent_Bean)
(SmartCouch_LoadCellSensor4_MassEvent_Bean))
and the function that used it would look something like
(deffunction average-weight ()
(bind ?result (run-query all-sensors))
(bind ?token (?result next))
(bind ?sum 0)
(foreach i (create$ 1 2 3 4)
(bind ?sum (+ ?sum (fact-slot-value (?token fact ?i) mass))))
(return (- (/ ?sum 4) 0.5)))
---------------------------------------------------------
Ernest Friedman-Hill
Science and Engineering PSEs Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
PO Box 969, MS 9012 [EMAIL PROTECTED]
Livermore, CA 94550 http://herzberg.ca.sandia.gov
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