Question

我试图在JessTab中找到温度观测值的平均值，这需要加入来自多个类的事实。以下规则：

(defrule averageOfObsValue  
?res <- 
(accumulate  
    (progn (bind ?s 0)(bind ?n 0)) 
    (progn (bind ?s (+ ?s ?v)) (++ ?n)) 
    (create$ ?n ?s ?qo) 
    (and  
        (object (is-a http..#ObservationValue) 
                (OBJECT ?ov)
                (http..#hasDataValue ?v)
        )
        (object (is-a http..#SensorOutput) 
                (OBJECT ?so) 
                (http..#hasValue ?ov)
        )
        (object (is-a http..#Observation)
                (OBJECT ?o)
                (http..#observationResult ?so)
                (http..#qualityOfObservation ?qo)
        )   
    )
)
=>  
(bind ?q (nth$ 3 ?res))  
(bind ?s (nth$ 2 ?res))  
(bind ?n (nth$ 1 ?res))  
(if (= (?q getURI) "http..#Temperature") then
(printout t "Average value is " (/ ?s ?n) " of " ?n " temperature observations." crlf)))

WM中的

具有以下形式：

(defrule MAIN::averageOfObsValue 
   (or 
     (and 
       (object (is-a http..#ObservationValue) 
               (OBJECT ?ov) 
               (http..#isValueOf ?so) 
               (http..#hasDataValue ?v))) 
     (and 
       (object (is-a http..#SensorOutput) 
               (OBJECT ?so) (http..#isObservationResultOf ?o))) 
     (and 
       (object (is-a http..#Observation) 
               (OBJECT ?o) (http..#qualityOfObservation ?qo)))) 
   => 
   (bind ?q (nth$ 3 ?res)) 
   (bind ?s (nth$ 2 ?res)) 
   (bind ?n (nth$ 1 ?res)) 
   (if (= (?q getURI) "http..#Temperature") then
   (printout t "Average value is " (/ ?s ?n) " of " ?n " temperature observations." crlf)))

并在运行时出现以下错误：

Jess报告了例程Context.getVariable中的错误执行时（n $ 3？res）执行时（bind？q（nth $ 3？res））执行默认MAIN :: averageOfObsValue655时执行（运行）时。消息：没有这样的变量res。计划文本：（运行）第137行。

Answer 1

似乎（并且您的最新观察证实）累积不能应用于具有连接的CE。最好的方法是创建临时事实，其中包含需要计算平均值的值，但必须注意创建不同的临时事实。

(deftemplate Value (slot v)(slot s)

(defrule createValueFacts
    (declare (salience 100))
    (object (is-a http..#ObservationValue) 
            (OBJECT ?ov)
            (http..#hasDataValue ?v)
    )
?s<-(object (is-a http..#SensorOutput) 
            (OBJECT ?so) 
            (http..#hasValue ?ov)
    )
    (object (is-a http..#Observation)
            (OBJECT ?o)
            (http..#observationResult ?so)
            (http..#qualityOfObservation ?qo)
    )
=>
    (assert (Value (v ?v)(s ?s))   ; using slot s to make fact unique
)

这些Value事实很容易累积：

(defrule averageOfObsValue 
?res <- (accumulate  
    (progn (bind ?s 0)(bind ?n 0)) 
    (progn (bind ?s (+ ?s ?v)) (++ ?n)) 
    (create$ ?n ?s) 
    (Value (v ?v)))
=>
(bind ?s (nth$ 2 ?res))  
(bind ?n (nth$ 1 ?res))  
(printout t "Average value is " (/ ?s ?n) " of " ?n " temperature observations." crlf))

复杂的条件元素在Jess规则中累积

1 个答案: