On 7 July 2011 08:25, Felix Chan <[email protected]> wrote:
> Hi,
>
> I am trying to find a way to write a rule that is based on comparing
> the number of one kind of facts and the number of another kind. I am
> sure experienced JESS users
Actually, Ernest has seen it a long time ago, and therefore we have...
> must have seen this requirement before and
> likely have a "standard", perhaps elegant way of dealing with it. But
> I am sorry to say that I am still struggling with it after some time.
>
... the CE accumulate!
(defrule getNumOfCars
?p <- (policy (policyId ?pid))
(car (policyId ?pid))
?c <- (accumulate (bind ?count 0)
(bind ?count (+ ?count 1))
?count
(car (policyId ?pid)))
=>
(modify ?p (numOfCars ?c))
)
(defrule getNumOfDrivers
?p <- (policy (policyId ?pid))
?c <- (accumulate (bind ?count 0)
(bind ?count (+ ?count 1))
?count
(driver (policyId ?pid)))
=>
(modify ?p (numOfDrivers ?c))
)
You can remove the queries.
-W
