55 lines
830 B
Go
55 lines
830 B
Go
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package onlinestats
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import "math"
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func SumSq(a []float64) float64 {
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var t float64
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for _, aa := range a {
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t += (aa * aa)
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}
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return t
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}
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func Sum(a []float64) float64 {
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var t float64
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for _, aa := range a {
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t += aa
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}
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return t
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}
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func Mean(a []float64) float64 {
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return Sum(a) / float64(len(a))
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}
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func variance(a []float64, sample bool) float64 {
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var adjustN float64
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if sample {
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adjustN = -1
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}
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m := Mean(a)
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var sum2 float64
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var sum3 float64
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for _, aa := range a {
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sum2 += (aa - m) * (aa - m)
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sum3 += (aa - m)
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}
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n := float64(len(a))
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return (sum2 - (sum3*sum3)/n) / (n + adjustN)
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}
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func Variance(a []float64) float64 {
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return variance(a, false)
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}
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func SampleVariance(a []float64) float64 {
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return variance(a, true)
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}
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func SampleStddev(a []float64) float64 {
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return math.Sqrt(SampleVariance(a))
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}
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