Added functionality to be able to remove elements from the window by providing a unique ID. Also, added another function to the interface that needs to be implemented by all the structs implementing this interface. This function should return a unique ID identifying the object so as to be able to distinguish between multiple instances of the same type.

utilities/runAvg/runAvg.go

@@ -6,11 +6,16 @@ One should implement Val() to be able to use this utility.
 
 package runAvg
 
-import "container/list"
+import (
+	"errors"
+	"container/list"
+)
 
 type Interface interface {
 	// Value to use for running average calculation.
 	Val() float64
+	// Unique ID
+	ID() string
 }
 
 type runningAverageCalculator struct {
@@ -61,14 +66,42 @@ func (rac *runningAverageCalculator) calculate(data Interface) float64 {
 	return rac.currentSum / float64(rac.window.Len())
 }
 
+/*
+If element with given ID present in the window, then remove it and return (removeElement, nil).
+Else, return (nil, error)
+*/
+func (rac *runningAverageCalculator) removeFromWindow(id string) (interface{}, error) {
+	for element := rac.window.Front(); element != nil; element = element.Next() {
+		if elementToRemove := element.Value.(Interface); elementToRemove.ID() == id {
+			rac.window.Remove(element)
+			return elementToRemove, nil
+		}
+	}
+	return nil, errors.New("Error: Element not found in the window.")
+}
+
 // Taking windowSize as a parameter to allow for sliding window implementation.
 func Calc(data Interface, windowSize int) float64 {
 	rac := getInstance(0.0, 0, windowSize)
 	return rac.calculate(data)
 }
 
+// Remove element from the window if it is present.
+func Remove(id string) (interface{}, error) {
+	// checking if racSingleton has been instantiated
+	if racSingleton == nil {
+		return nil, errors.New("Error: Not instantiated. Please call Init() to instantiate.")
+	} else {
+		return racSingleton.removeFromWindow(id)
+	}
+}
+
 // initialize the parameters of the running average calculator
 func Init() {
+	// checking to see if racSingleton needs top be instantiated
+	if racSingleton == nil {
+		racSingleton = getInstance(0.0, 0, 0)
+	}
 	// Setting parameters to default values. Could also set racSingleton to nil but this leads to unnecessary overhead of creating
 	// another instance when Calc is called.
 	racSingleton.window.Init()