78 lines
2.2 KiB
Go
78 lines
2.2 KiB
Go
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/*
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A utility to calculate the running average.
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One should implement Val() to be able to use this utility.
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*/
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package runAvg
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import "container/list"
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type Interface interface {
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// Value to use for running average calculation.
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Val() float64
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}
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type runningAverageCalculator struct {
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window list.List
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windowSize int
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currentSum float64
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numberOfElementsInWindow int
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}
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// singleton instance
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var racSingleton *runningAverageCalculator
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// return single instance
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func getInstance(curSum float64, n int, wSize int) *runningAverageCalculator {
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if racSingleton == nil {
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racSingleton = &runningAverageCalculator {
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windowSize: wSize,
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currentSum: curSum,
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numberOfElementsInWindow: n,
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}
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return racSingleton
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} else {
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// Updating window size if a new window size is given.
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if wSize != racSingleton.windowSize {
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racSingleton.windowSize = wSize
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}
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return racSingleton
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}
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}
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// Compute the running average by adding 'data' to the window.
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// Updating currentSum to get constant time complexity for every running average computation.
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func (rac *runningAverageCalculator) calculate(data Interface) float64 {
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if rac.numberOfElementsInWindow < rac.windowSize {
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rac.window.PushBack(data)
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rac.numberOfElementsInWindow++
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rac.currentSum += data.Val()
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} else {
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// removing the element at the front of the window.
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elementToRemove := rac.window.Front()
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rac.currentSum -= elementToRemove.Value.(Interface).Val()
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rac.window.Remove(elementToRemove)
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// adding new element to the window
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rac.window.PushBack(data)
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rac.currentSum += data.Val()
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}
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return rac.currentSum / float64(rac.window.Len())
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}
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// Taking windowSize as a parameter to allow for sliding window implementation.
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func Calc(data Interface, windowSize int) float64 {
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rac := getInstance(0.0, 0, windowSize)
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return rac.calculate(data)
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}
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// initialize the parameters of the running average calculator
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func Init() {
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// Setting parameters to default values. Could also set racSingleton to nil but this leads to unnecessary overhead of creating
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// another instance when Calc is called.
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racSingleton.window.Init()
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racSingleton.windowSize = 0
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racSingleton.currentSum = 0.0
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racSingleton.numberOfElementsInWindow = 0
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}
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